S = sorted(map(int, input().split()))
a = S[0]
for i in range(3):
    S[i] -= a
b = (S[2] - S[1]) // 2
a += b
S[1] -= b
S[2] -= b * 3
b = S[1] // 4
a += b * 2
S[1] -= b * 4
S[2] -= b * 4
if S[2] > 2:
    a += 1
print(a)