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

int gcm(int a, int b)
{
  return (b == 0) ? a : gcm(b, a % b);
}

int main()
{
  int a, b, t, g;
  printf("Input two integer.\n> ");
  if (scanf("%d %d", &a, &b) == 2) {
    if (b > a) {
      t = a;
      a = b;
      b = t;
    }
    printf("gcm: %d\n", g = gcm(a, b));
    printf("lcm: %d\n", a * b / g);
  }
  return 0;
}
/* end */

Input two integer.
>