import sys

def inp():
	for i in sys.stdin:
		xa,ya,xb,yb,xc,yc,xd,yd = map(float, i.split(","))	
		print hantei(xa,ya,xb,yb,xc,yc,xd,yd)

def hantei(xa,ya,xb,yb,xc,yc,xd,yd):
	count = [0,0,0,0]
	a1 = (ya - yc)/(xa - yc)
	b1 = ya - a1*xa

	a2 = (yb - yd)/(xb - xd)
	b2 = yb - a2*xb

	if xb*a1+b1 > yb:
		count[0] += 1
	else:
		count[1] += 1
	if xd*a1+b1 > yd:
		count[0] += 1
	else:
		count[1] += 1
	if xa*a2+b2 > ya:
		count[2] += 1
	else:
		count[3] += 1
	if xc*a2+b2 > yc:
		count[2] += 1
	else:
		count[3] += 1

	for i in xrange(4):
		if count[i] != 1:
			return "NO"
		else:
			pass
	return "YES"

if __name__ == "__main__":
	inp()