#include <numeric>
#include <iostream>
#include <vector>
using namespace std;

int main() {
    long long N;
    cin >> N;

    for (int k = 2; k <= 70; ++k) {
        vector<__int128> vs(k + 1);
        vs.back() = 1;
        while (vs.back() < N) {
            __int128 sum = std::accumulate(vs.end() - k, vs.end(), __int128(0));
            vs.push_back(sum);
        }
        if (vs.back() == N) {
            cout << k << '\n';
            return 0;
        }
    }

    puts("-1");
}