import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
dij = [(0, 1), (1, 0), (1, 1), (1, -1)]
inf = 10**19
# md = 998244353
md = 10**9+7

def solve():
    if aa[0] == 1:
        if aa[1] == 1 or aa[1] == 2:
            for i in range(2, 5):
                if aa[i] != aa[i-1]+aa[i-2]:
                    return i
            return 5
        return 1

    a = b = 1
    while a < aa[0]: a, b = b, a+b
    if a != aa[0]: return 0
    if b != aa[1]: return 1
    for i in range(2, 5):
        if aa[i] != aa[i-1]+aa[i-2]:
            return i
    return 5

aa = [II() for _ in range(5)]
aa.reverse()
print(solve())