#include <bits/stdc++.h>
int main(void) {
  double x1, x2, x3, x4, y1, y2, y3, y4;
  double sya1, sya2;
  while (scanf("%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf", &x1, &y1, &x2, &y2, &x3, &y3,
               &x4, &y4) != EOF) {
    sya1 = (x3 - x1) / (y3 - y1);
    sya2 = (x4 - x2) / (y4 - y2);
    if (sya1 < 0) sya1 = -sya1;
    if (sya2 < 0) sya2 = -sya2;
    if (y3 - y2 > sya1 * x3 - x2 && y4 - y1 > sya1 * x4 - x1 &&
        y4 - y1 > sya2 * x1 - x4 && y3 - y2 > sya2 * x2 - x3)
      printf("YES\n");
    else
      printf("NO\n");
  }
  return 0;
}
