15.py

arr = [int(i) for i in input().split()]

nod = 0
for i in range(len(arr) - 1):
    a, b = arr[i], arr[i + 1]
    while a != b:
        if a > b:
            a -= b
        else:
            b -= a
    arr[i + 1] = a

print(arr[-1])