#include<cstdio>
#include<iostream>

using namespace std;

int main(void){

	char gava;
	double xa,ya,xb,yb,xc,yc,xd,yd;
	double a,b;
	int flag;

	while(cin>>xa>>gava>>ya>>gava>>xb>>gava>>yb>>gava>>xc>>gava>>yc>>gava>>xd>>gava>>yd){
		flag=1;

		if(xa-xc==0) a=0;
		else a=(ya-yc)/(xa-xc);
		if(xa*xc==0) b=0;
		else b=(xa*yc-ya*xc)/(xa*xc);
		if(yd<a*xd+b&&yb<a*xb+b||yd>a*xd+b&&yb>a*xb+b) flag=0;

		if(xb-xd==0) a=0;
		else a=(yb-yd)/(xb-xd);
		if(xb*xd==0) b=0;
		else b=(xb*yd-yb*xd)/(xb*xd);
		if(yc<a*xc+b&&ya<a*xa+b||yc>a*xc+b&&ya>a*xa+b) flag=0;

		if(flag==1) cout<<"YES"<<endl;
		else cout<<"NO"<<endl;
	}

	return 0;
}