#include <bits/stdc++.h>
using namespace std;
int main(void) {
  double x1, y1, x2, y2, x3, y3, x4, y4;
  while (scanf("%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf", &x1, &y1, &x2, &y2, &x3, &y3,
               &x4, &y4) != EOF) {
    if (x1 + x2 == x3 + x4 && y1 + y2 == y3 + y4)
      puts("YES");
    else if (x1 + x3 == x2 + x4 && y1 + y3 == y2 + y4)
      puts("YES");
    else if (x1 + x4 == x3 + x2 && y1 + y4 == y3 + y2)
      puts("YES");
    else
      puts("NO");
  }
  return 0;
}
