R,G,B = map(int,input().split())
ok = min(R, G, B)
ng = max(R, G, B) + 1
while ng - ok > 1:
    M = (ok + ng) // 2
    P = 0
    Q = 0
    if R > M:
        P += (R - M) // 2
    else:
        Q += M - R
    if G > M:
        P += (G - M) // 2
    else:
        Q += M - G
    if B > M:
        P += (B - M) // 2
    else:
        Q += M - B
    if P >= Q:
        ok = M
    else:
        ng = M
print(ok)