#include<iostream>
#include<cmath>
int main()
{
	while (true)
	{
		double xa, ya, xb, yb, xc, yc, xd, yd;
		char foo;
		std::cin >> xa >> foo >> ya >> foo >> xb >> foo >> yb >> foo >> xc >> foo >> yc >> foo >> xd >> foo >> yd;
		if (std::cin.eof())
		{
			break;
		}
		const long double A_C = std::hypot(xa - xc, ya - yc);
		const long double B_D = std::hypot(xb - xd, yb - yd);
		const long double A_BD = std::abs((yd - yb) * (xa - xd) - (xd - xb) * (ya - yd)) / std::hypot(yd - yb, xd - xb);
		const long double B_AC = std::abs((yc - ya) * (xb - xc) - (xc - xa) * (yb - yc)) / std::hypot(yc - ya, xc - xa);
		std::cout << (A_C > A_BD && B_D > B_AC ? "YES" : "NO") << std::endl;
	}
	return 0;
}
