for code java public class Solution { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String S = sc.nextLine(); try{ int num = Integer.parseInt(S);
System.out.println(num); }catch(Exception e){ System.out.println("Bad String"); }

}

}

public class Solution { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String S = sc.nextLine(); try{ int num = Integer.parseInt(S);
System.out.println(num); }catch(Exception e){ System.out.println("Bad String"); }

            for java code 



}

}

for js

function main() { const S = readLine();console.log(parseInt(S)?S:'Bad String') }

If anyone is trying to solve this problem in Python3. Then use this code not the pre-defined code:

#!/bin/python3

import math
import os
import random
import re
import sys

S = input().strip()
try:
    print(int(S))
except ValueError:
    print("Bad String")

For JS this worked:

function main() {
  const S = readLine();
  try {
    const num = JSON.parse(S);
    console.log(num);
  } catch (e) {
    console.log("Bad String");
  }
}

But for Python I get: Error reading result file.You should use exception handling concepts.

I tried this:

    S = input()
    
    try:
        num=int(S)
        print(num)
    except ValueError: 
        print("Bad String")

and this:

    S = input()
    
    try:
        num=int(S)
        print(num)
    except: 
        raise Exception("Bad String")

None of these worked.