const lines = require('fs')
  .readFileSync('/dev/stdin', 'utf-8')
  .trim().split('\n').values();

let N = lines.next().value;
let ans = [];

N = [...N].reverse();

for (let i = 0; i < N.length; i++) {
  ans.push(N[i]);
  if (i % 3 === 2 && i < N.length - 1) ans.push(',');
}

console.log(ans.reverse().join(''));