/* -*- coding: utf-8 -*-
 *
 * 954.cc:  No.954 Result - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int N = 5;

/* typedef */

typedef long long ll;

/* global variables */

ll as[N];

/* subroutines */

/* main */

int main() {
  for (int i = N - 1; i >= 0; i--) scanf("%lld", as + i);

  int maxn = 0;
  for (ll f0 = 0, f1 = 1; f1 <= as[0];) {
    if (f1 == as[0]) {
      int n = 1;
      ll g0 = f0, g1 = f1;
      while (n < N && g0 + g1 == as[n]) {
	n++;
	ll g2 = g1 + g0;
	g0 = g1, g1 = g2;
      }
      if (maxn < n) maxn = n;
    }

    ll f2 = f1 + f0;
    f0 = f1, f1 = f2;
  }

  printf("%d\n", maxn);
  return 0;
}