551 B | 551 chars
import sys
from math import sqrt, pi, sin, factorial
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = " " : [*map(int,inp().split(x))]
mfi = lambda x = " " : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def f(a, b):
return f(b, a % b) if b > 0 else a
def solve():
while 1:
a, b, c, d = mii()
if a == b == c == d == 0:
break
k = f(a, b)
k = f(k, c)
k = f(k, d)
p(k)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
solve()