#include <stdio.h>
#include <math.h>
#include <algorithm>
using namespace std;


int main() {
	double x1, x2, x3, x4, y1, y2, y3, y4, dist1, dist2, dist3, dist4, dist5, dist6;

	while (scanf("%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf", &x1, &y1, &x2, &y2, &x3, &y3, &x4, &y4) != EOF) {
		dist1 = sqrt((x1 - x3) * (x1 - x3) + (y1 - y3) * (y1 - y3));
		dist2 = sqrt((x2 - x4) * (x2 - x4) + (y2 - y4) * (y2 - y4));
		dist3 = fabs((y2 - y4) * x1 + (x4 - x2) * y1 + y2 * (x2 - x4) - x2 * (y2 - y4)) / (sqrt((y2 - y4) * (y2 - y4) + (x4 - x2) * (x4 - x2)));
		dist4 = fabs((y1 - y3) * x2 + (x3 - x1) * y2 + y1 * (x1 - x3) - x1 * (y1 - y3)) / (sqrt((y1 - y3) * (y1 - y3) + (x3 - x1) * (x3 - x1)));
		dist5 = fabs((y2 - y4) * x3 + (x4 - x2) * y3 + y2 * (x2 - x4) - x2 * (y2 - y4)) / (sqrt((y2 - y4) * (y2 - y4) + (x4 - x2) * (x4 - x2)));
		dist6 = fabs((y1 - y3) * x4 + (x3 - x1) * y4 + y1 * (x1 - x3) - x1 * (y1 - y3)) / (sqrt((y1 - y3) * (y1 - y3) + (x3 - x1) * (x3 - x1)));

		if (dist1 < dist3 || dist2 < dist4 || dist1 < dist5 || dist2 < dist6) {
			printf("NO\n");
		}
		else {
			printf("YES\n");
		}
	}

	return 0;
}
