#include<stdio.h>

int R_1_or_L_2(
    double x1,double y1,
    double x2,double y2,
    double x3,double y3){
  int i;

  if(x1==x2)
    return (y1<y2)?
      (x3>x1?1:2):
      (x3<x1?1:2);
  if(y1==y2)
    return (x1<x2)?
      (y3<y1?1:2):
      (y3>y1?1:2);
  if(y3<(x3-x1)*(y2-y1)/(x2-x1)+y1)
    return (x1<x2)?1:2;
  return (x2<x1)?1:2;
}

int main(void){
  double x[4],y[4];
  char hoge;

  for(;scanf("%lf%c%lf%c%lf%c%lf%c%lf%c%lf%c%lf%c%lf",
        &x[0],&hoge,&y[0],&hoge,
        &x[1],&hoge,&y[1],&hoge,
        &x[2],&hoge,&y[2],&hoge,
        &x[3],&hoge,&y[3])==15;){

    if(
        (R_1_or_L_2(x[0],y[0],x[1],y[1],x[2],y[2])
         ==
         R_1_or_L_2(x[0],y[0],x[2],y[2],x[3],y[3]))
        &&
        (R_1_or_L_2(x[0],y[0],x[2],y[2],x[3],y[3])
         ==
         R_1_or_L_2(x[1],y[1],x[2],y[2],x[3],y[3]))
      )
      printf("YES\n");
    else
      printf("NO\n");
  }

  return 0;
}