#include<iostream>
#include<cstdio>
using namespace std;
int main(){
	double x[4],y[4];
	while(scanf("%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf",&x[0],&y[0],&x[1],&y[1],&x[2],&y[2],&x[3],&y[3])!=EOF){
		if(x[0]==x[2]){
			if(x[0]<x[1]&&x[0]<x[3])
				cout<<"NO"<<endl;
			else if(x[0]>x[1]&&x[0]>x[3])
				cout<<"NO"<<endl;
			else cout<<"YES"<<endl;
		}
		else if(x[1]==x[3]){
			if(x[1]<x[0]&&x[1]<x[2])
				cout<<"NO"<<endl;
			else if(x[1]>x[0]&&x[1]>x[2])
				cout<<"NO"<<endl;
			else cout<<"YES"<<endl;
		}
		else {
			if(y[1]>((y[2]-y[0])/(x[2]-x[0]))*(x[1]-x[0])+y[0]&&y[3]>((y[2]-y[0])/(x[2]-x[0]))*(x[3]-x[0])+y[0])
			cout<<"NO"<<endl;
			else  if(y[1]<((y[2]-y[0])/(x[2]-x[0]))*(x[1]-x[0])+y[0]&&y[3]<((y[2]-y[0])/(x[2]-x[0]))*(x[3]-x[0])+y[0])
			cout<<"NO"<<endl;
			else if(y[0]>((y[3]-y[1])/(x[3]-x[1]))*(x[0]-x[1])+y[1]&&y[2]>((y[3]-y[1])/(x[3]-x[1]))*(x[2]-x[1])+y[1])
			cout<<"NO"<<endl;
			else if(y[0]<((y[3]-y[1])/(x[3]-x[1]))*(x[0]-x[1])+y[1]&&y[2]<((y[3]-y[1])/(x[3]-x[1]))*(x[2]-x[1])+y[1])
			cout<<"NO"<<endl;
			else cout<<"YES"<<endl;
		}
	}
	return 0;
}