#include <bits/stdc++.h>
using namespace std;
int main() {
  double xa, ya, xb, yb, xc, yc, xd, yd, xe, ye;
  double tac, tbd, sac, sbd;
  char c[10000];
  int i;
  while (scanf("%s", &c) != EOF) {
    xa = atof(strtok(c, ","));
    ya = atof(strtok(NULL, ","));
    xb = atof(strtok(NULL, ","));
    yb = atof(strtok(NULL, ","));
    xc = atof(strtok(NULL, ","));
    yc = atof(strtok(NULL, ","));
    xd = atof(strtok(NULL, ","));
    yd = atof(strtok(NULL, ","));
    sac = (yc - ya) / (xc - xa);
    tac = ya - xa * sac;
    sbd = (yd - yb) / (xd - xb);
    tbd = yb - xb * sbd;
    xe = (tac - tbd) / (sbd - sac);
    ye = xe * sac + tac;
    if (((xa <= xe && xe <= xc) || (xc <= xe && xe <= xa)) &&
        ((ya <= ye && ye <= yc) || (yc <= ye && ye <= ya))) {
      cout << "YES" << endl;
    } else {
      cout << "NO" << endl;
    }
  }
  return 0;
}
