from collections import deque
from itertools import combinations

lines = (int(x.strip()) for x in open("input.txt"))
L = 25

buffer = deque(maxlen=L)

for line in lines:
    if len(buffer) == L:
        found = any(a + b == line for a, b in combinations(buffer, 2))
        if not found:
            print(line)
            break
    buffer.append(line)