#include<iostream>
#include <cstdio>
#include <math.h>

using namespace std;

int main(void){
    double x1,y1,x2,y2,x3,y3,x4,y4;
    
    while (scanf("%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf",&x1,&y1,&x2,&y2,&x3,&y3,&x4,&y4) != EOF) {
        if( x1+x2 == x3+x4 && y1+y2 == y3+y4 )puts("YES");
        else if( x1+x3 == x2+x4 && y1+y3 == y2+y4)puts("YES");
        else if( x1+x4 == x3+x2 && y1+y4 == y3+y2 )puts("YES");
        else puts("NO");
    }
    return 0;
}