#include <stdio.h>
#include <stdlib.h>

void int_comma(int num)
{
  if (num < 0) {        /* display sign for negatives */
    printf("-");
    num = -num;
  }
  if (num < 1000)
    printf("%3d", num);
  else {
    int_comma(num / 1000);
    printf(",%03d", num % 1000);
  }
}

int main(int argc, char * argv[])
{
  int num;
  if (argc < 2) {
    printf("usage: int_comma <number>\n");
    return -1;
  }
  num = atoi(argv[1]);
  int_comma(num);
  printf("\n");
  return 0;
}