diff --git a/verify-account-ui/script.js b/verify-account-ui/script.js
index 6df6bf0..fe883d8 100644
--- a/verify-account-ui/script.js
+++ b/verify-account-ui/script.js
@@ -1,4 +1,5 @@
 const codes = document.querySelectorAll('.code')
+const length = codes.length
 
 codes[0].focus()
 
@@ -6,8 +7,14 @@ codes.forEach((code, idx) => {
     code.addEventListener('keydown', (e) => {
         if(e.key >= 0 && e.key <=9) {
             codes[idx].value = ''
+            if(length - 1 == idx) {
+              return  
+            }
             setTimeout(() => codes[idx + 1].focus(), 10)
         } else if(e.key === 'Backspace') {
+            if(idx == 0) {
+              return   
+            }
             setTimeout(() => codes[idx - 1].focus(), 10)
         }
     })