from sys import stdin


def main():
    input = lambda: stdin.readline()[:-1]
    X, Y, Z = map(int, input().split())

    if min(X, Y) + Z <= max(X, Y):
        ans = min(X, Y) + Z
    else:
        d = min(X, Y) + Z - max(X, Y)
        ans = max(X, Y) + d // 2
    print(ans)

main()