Online Java Compiler

import java.io.*; import java.util.Scanner; class CountSubString { int countSubStr(char str[],int n) { int res = 0; // Initialize result // Pick a starting point for (int i = 0; i<n; i++) { if (str[i] == '1') { // Search for all possible ending point for (int j = i + 1; j< n; j++) { if (str[j] == '1') res++; } } } return res; } public static void main(String[] args) { CountSubString count = new CountSubString(); Scanner sc = new Scanner(System.in); int n = sc.nextInt(); String string = String.valueOf(n); char str[] = string.toCharArray(); System.out.println(count.countSubStr(str,n)); } }