import sys
from math import sqrt, pi, sin, factorial
inp = lambda : sys.stdin.readline()[:-1]
mii = lambda x = " ": [*map(int,inp().split(x))]
mfi = lambda x = " ": [*map(float,inp().split(x))]
ii = lambda : int(inp())
l = mii()
d = []
for i in range(10):
for j in range(i + 1, 10):
d.append(l[i] or l[j])
for i in range(10):
for j in range(i + 1, 10):
for k in range(j + 1, 10):
d.append(l[i] or l[j] or l[k])
k = d[0]
for i in range(1, len(d)):
k ^= d[i]
print(k)