from collections import deque, defaultdict, Counter
from functools import lru_cache,reduce
from bisect import bisect_left, bisect_right
from heapq import heappop, heappush
from itertools import accumulate,permutations
#from more_itertools import distinct_permutations as dispermutations
from math import *
import sys
from typing import List
input = sys.stdin.readline
def R(): return int(input())
def RS():return input().rstrip()
def RSS():return [c for c in input().rstrip()]
def RLS():return input().rstrip().split()
def RR(): return [int(x) for x in input().split()]
def get_pre(nums): return list(accumulate(nums))
from operator import xor,or_,and_

a,b,c=RR()
ans=a
if a>80:
    ans+=b
    if b>40:ans+=c

if ans>=250:
    print(1)
elif ans>=220:
    print(2)
elif ans>=175:
    print(3)
else:
    print(-1)