import sys import math import bisect import heapq from collections import deque, defaultdict #160427717982164055zq # ------------------------------------------------- def ST(): return input().rstrip() def IN(): return int(input()) def ML(typ=int): return [typ(x) for x in input().split()] def IL(): return ML() T = IL() ans = 6000 for i in range(7): if T[i] == -1: ans = -1 else: ans -= T[i] if ans < 0: print(-1) else: print(ans)