#include <bits/stdc++.h>
using namespace std;

using ll = long long;

int main() {
    ll fib[75];
    fib[0] = 1;
    fib[1] = 1;
    for (int i = 2; i < 75; i++) {
        fib[i] = fib[i - 1] + fib[i - 2];
    }

    vector<ll> a(5);
    for (int i = 0; i < 5; i++) {
        cin >> a.at(i);
    }
    reverse(a.begin(), a.end());

    int maxi = 0;
    for (int i = 0; i < 70; i++) {
        int cnt = 0;
        for (int j = 0; j < 5; j++) {
            if (a[j] != fib[i + j]) break;
            cnt++;
        }
        maxi = max(maxi, cnt);
    }
    cout << maxi << endl;
}