#include <iostream>
#include <cmath>

using namespace std;

double tri2s(double xa, double ya, double xb, double yb, double xc, double yc){
     double a, b, c, s;
    
     a = sqrt((xb - xc) * (xb - xc) + (yb - yc) * (yb - yc));
     b = sqrt((xa - xc) * (xa - xc) + (ya - yc) * (ya - yc));
     c = sqrt((xb - xa) * (xb - xa) + (yb - ya) * (yb - ya));
    
     s = (a+b+c) / 2;
    
     return sqrt(s * (s - a) * (s - b) * (s - c));
}

int main(void){
     double x[4], y[4];
     double sq;
     double tri[4];
     bool isok = true;
    
     while(cin >> x[0]){
          cin.ignore(); cin >> y[0];
          cin.ignore(); cin >> x[1]; cin.ignore(); cin >> y[1];
          cin.ignore(); cin >> x[2]; cin.ignore(); cin >> y[2];
          cin.ignore(); cin >> x[3]; cin.ignore(); cin >> y[3];
         
          sq = tri2s(x[0], y[0], x[1], y[1], x[2], y[2]) + tri2s(x[0],y[0],x[2],y[2],x[3],y[3]);
         
          tri[0] = tri2s(x[0], y[0], x[1], y[1], x[2], y[2]);
          tri[1] = tri2s(x[0], y[0], x[1], y[1], x[3], y[3]);
          tri[2] = tri2s(x[0], y[0], x[2], y[2], x[3], y[3]);
          tri[3] = tri2s(x[1], y[1], x[2], y[3], x[3], y[3]);
         
          for(int i=0;i<4;i++){
               if(tri[i] > sq) isok = false;
          }
         
          if(isok){
               cout << "YES" << endl;
          }else{
               cout << "NO" << endl;
          }
          isok = true;0
     }
     return 0;
}