def f(num, k):
ret = 0
for i in num:
ret *= k
a = 0
if '0' <= i <= '9':
a = int(i)
else:
a = 10 + ord(i) - 65
if a >= k:
return -1
ret += a
return ret
x, c = input().split("=")
a,b = x.split("+")
for i in range(2, 37):
if f(a, i) + f(b, i) == f(c, i):
print(i)
break