def NWD(a, b):
	while b != 0:
		c = a % b
		a = b
		b = c
        
	return a

a = 210
b = 150
c = 90
d = 60

nwdA_B = NWD(a, b)
nwdC_D = NWD(c, d)
nwdA_B_C_D = NWD(nwdA_B, nwdC_D)

print(nwdA_B_C_D)