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

ll n, f[200010];

bool check(ll k)
{
    for (int i=1; i<k; i++) f[i] = 0;
    f[k] = 1;
    for (int i=k+1; i<=100; i++) 
    {
        f[i] = 0;
        for (int j=i-1; j>=i-k; j--) f[i] += f[j];
        if (f[i] == n) return true;
        else if (f[i] > n) return false;
    }
    return false;
}

int main()
{
    cin >> n;
    for (int i=1; i<=n; i++) if (check(i))
    {
        cout << i;
        return 0;
    }
    cout << -1;
}