diff --git a/__crypto/btc-address/src/main.rs b/__crypto/btc-address/src/main.rs
index dbcc646..b585307 100644
--- a/__crypto/btc-address/src/main.rs
+++ b/__crypto/btc-address/src/main.rs
@@ -30,14 +30,20 @@ fn main() {
         .unwrap_or_else(|_| 10_000_000_u64);
     println!("LOOP_COUNT={}", loop_count);
 
+
     let num_of_vcpus = num_cpus::get();
     let num_of_phycpus = num_cpus::get_physical();
     println!("You have {} vCPUs, from {} phyCPUs", num_of_vcpus, num_of_phycpus);
+    let concurrent_count = std::env::var("CONCURRENT_COUNT")
+        .map(|c| c.parse::<u64>())
+        .unwrap_or_else(|_| Ok(num_of_phycpus as u64))
+        .unwrap_or_else(|_| 1_u64);
+    println!("CONCURRENT_COUNT={}", concurrent_count);
 
     let stop_flag = Arc::new(Mutex::new(false));
     let mut handles = vec![];
-    for ind in 0..num_of_phycpus {
-        println!("- Running task {} of {}", ind, num_of_phycpus);
+    for ind in 0..concurrent_count {
+        println!("- Running task {} of {}", ind, concurrent_count);
         let the_stop_flag = Arc::clone(&stop_flag);
         let prefixes = prefixes.clone();
         let child = thread::spawn(move || {
@@ -51,7 +57,7 @@ fn main() {
     println!("Finished!");
 }
 
-fn run_one_task(prefixes: Vec<String>, continue_on_found: bool, loop_count: u64, ind: usize, the_stop_flag: Arc<Mutex<bool>>) {
+fn run_one_task(prefixes: Vec<String>, continue_on_found: bool, loop_count: u64, ind: u64, the_stop_flag: Arc<Mutex<bool>>) {
     let secp = Secp256k1::new();
     let mut rng = OsRng::new().expect("OsRng");