diff --git a/Cargo.lock b/Cargo.lock
index aea90c9..6999210 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -26,6 +26,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.95"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34ac096ce696dc2fcabef30516bb13c0a68a11d30131d3df6f04711467681b04"
+
 [[package]]
 name = "autocfg"
 version = "1.4.0"
@@ -253,21 +259,6 @@ version = "0.1.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3a471a38ef8ed83cd6e40aa59c1ffe17db6855c18e3604d9c4ed8c08ebc28678"
 
-[[package]]
-name = "futures"
-version = "0.3.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "65bc07b1a8bc7c85c5f2e110c476c7389b4554ba72af57d8445ea63a576b0876"
-dependencies = [
- "futures-channel",
- "futures-core",
- "futures-executor",
- "futures-io",
- "futures-sink",
- "futures-task",
- "futures-util",
-]
-
 [[package]]
 name = "futures-channel"
 version = "0.3.31"
@@ -275,7 +266,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2dff15bf788c671c1934e366d07e30c1814a8ef514e1af724a602e8a2fbe1b10"
 dependencies = [
  "futures-core",
- "futures-sink",
 ]
 
 [[package]]
@@ -300,18 +290,6 @@ version = "0.3.0-alpha.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b35b6263fb1ef523c3056565fa67b1d16f0a8604ff12b11b08c25f28a734c60a"
 
-[[package]]
-name = "futures-executor"
-version = "0.3.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e28d1d997f585e54aebc3f97d39e72338912123a67330d723fdbb564d646c9f"
-dependencies = [
- "futures-core",
- "futures-task",
- "futures-util",
- "num_cpus",
-]
-
 [[package]]
 name = "futures-executor-preview"
 version = "0.3.0-alpha.19"
@@ -323,29 +301,12 @@ dependencies = [
  "num_cpus",
 ]
 
-[[package]]
-name = "futures-io"
-version = "0.3.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e5c1b78ca4aae1ac06c48a526a655760685149f0d465d21f37abfe57ce075c6"
-
 [[package]]
 name = "futures-io-preview"
 version = "0.3.0-alpha.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f4914ae450db1921a56c91bde97a27846287d062087d4a652efc09bb3a01ebda"
 
-[[package]]
-name = "futures-macro"
-version = "0.3.31"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "162ee34ebcb7c64a8abebc059ce0fee27c2262618d7b60ed8faf72fef13c3650"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "futures-preview"
 version = "0.3.0-alpha.19"
@@ -384,16 +345,10 @@ version = "0.3.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9fa08315bb612088cc391249efdc3bc77536f16c91f6cf495e6fbe85b20a4a81"
 dependencies = [
- "futures-channel",
  "futures-core",
- "futures-io",
- "futures-macro",
- "futures-sink",
  "futures-task",
- "memchr",
  "pin-project-lite",
  "pin-utils",
- "slab",
 ]
 
 [[package]]
@@ -402,7 +357,7 @@ version = "0.3.0-alpha.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5ce968633c17e5f97936bd2797b6e38fb56cf16a7422319f7ec2e30d3c470e8d"
 dependencies = [
- "futures 0.1.31",
+ "futures",
  "futures-channel-preview",
  "futures-core-preview",
  "futures-io-preview",
@@ -629,7 +584,7 @@ checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 name = "leetcode-rust"
 version = "0.1.0"
 dependencies = [
- "futures 0.3.31",
+ "anyhow",
  "rand",
  "regex",
  "reqwest",
@@ -1231,7 +1186,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "57fc868aae093479e3131e3d165c93b1c7474109d13c90ec0dda2a1bbfff0674"
 dependencies = [
  "bytes 0.4.12",
- "futures 0.1.31",
+ "futures",
  "log",
 ]
 
@@ -1407,7 +1362,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "83420b37346c311b9ed822af41ec2e82839bfe99867ec6c54e2da43b7538771c"
 dependencies = [
  "cfg-if 0.1.10",
- "futures 0.1.31",
+ "futures",
  "futures-channel-preview",
  "futures-util-preview",
  "js-sys",
diff --git a/Cargo.toml b/Cargo.toml
index 19aa71c..d14d1a0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,9 +11,9 @@ serde_json = "1.0"
 serde_derive = "1.0"
 rand = "0.8.5"
 regex = "1.3.4"
-futures = { version = "0.3.11", features = ["thread-pool"] }
 surf = "1.0.3"
 tokio = { version = "1.0.0", features = ["rt", "rt-multi-thread", "macros"] }
+anyhow = "1.0.95"
 
 [lib]
 doctest = false
diff --git a/src/main.rs b/src/main.rs
index 2d32b98..a83d6df 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,10 @@
 use crate::fetch_problem::{Fetcher, ProblemManager};
 use std::fs;
+use std::fs::exists;
 use std::io::Write;
 use std::path::Path;
+use anyhow::anyhow;
+use serde::de::Error;
 
 mod fetch_problem;
 
@@ -41,8 +44,13 @@ async fn main() {
     }
 }
 
-fn write_file(file_name: &String, file_content: &String) -> std::io::Result<()> {
+fn write_file(file_name: &String, file_content: &String) -> anyhow::Result<()> {
     let file_path = Path::new("./src/problem").join(format!("{}.rs", file_name));
+    
+    if exists(&file_path)? {
+        println!("{} has pulled.", file_name);
+        return Err(anyhow!("{} has pulled", file_name));
+    }
 
     let mut file = fs::OpenOptions::new()
         .write(true)
@@ -58,5 +66,6 @@ fn write_file(file_name: &String, file_content: &String) -> std::io::Result<()>
         .append(true)
         .open("./src/problem/mod.rs")?;
 
-    write!(mod_file, "\nmod {};", file_name)
+    write!(mod_file, "\nmod {};", file_name)?;
+    Ok(())
 }