import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
sys.setrecursionlimit(10 ** 7)

x, y, z = map(int, readline().split())
if x + z < y:
    print(x + z)
elif y + z < x:
    print(y + z)
else:
    print((x + y + z) // 2)