#include <bits/stdc++.h>
double get_degree(double ox, double oy, double ax, double ay, double bx,
                  double by) {
  double deg_oa;
  double deg_ob;
  if (fabs(ox - ax) < 0.000001) {
    if (oy > ay) {
      deg_oa = 270;
    } else {
      deg_oa = 90;
    }
  } else if (fabs(oy - ay) < 0.000001) {
    if (ox > ax) {
      deg_oa = 180;
    } else {
      deg_oa = 0;
    }
  } else if (ox < ax) {
    deg_oa = atan((ay - oy) / (ax - ox)) * 180 / M_PI;
  } else {
    deg_oa = -(atan((ay - oy) / (ax - ox)) * 180 / M_PI);
  }
  if (fabs(ox - bx) < 0.000001) {
    if (oy > by) {
      deg_ob = 270;
    } else {
      deg_ob = 90;
    }
  } else if (fabs(oy - by) < 0.000001) {
    if (ox > bx) {
      deg_ob = 180;
    } else {
      deg_ob = 0;
    }
  } else if (ox < bx) {
    deg_ob = atan((by - oy) / (bx - ox)) * 180 / M_PI;
  } else {
    deg_ob = -(atan((by - oy) / (bx - ox)) * 180 / M_PI);
  }
  return fmod(deg_ob - deg_oa + 720, 360);
}
int main(void) {
  double xa, ya, xb, yb, xc, yc, xd, yd;
  double deg[4];
  while (scanf("%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf\n", &xa, &ya, &xb, &yb, &xc,
               &yc, &xd, &yd) == 8) {
    deg[0] = get_degree(xa, ya, xb, yb, xd, yd);
    deg[1] = get_degree(xb, yb, xc, yc, xa, ya);
    deg[2] = get_degree(xc, yc, xd, yd, xb, yb);
    deg[3] = get_degree(xd, yd, xa, ya, xc, yc);
    if (deg[0] <= 180 && deg[1] <= 180 && deg[2] <= 180 && deg[3] <= 180) {
      printf("Yes\n");
    } else {
      printf("No\n");
    }
  }
  return 0;
}
