1037A - Packets - CodeForces Solution

#define ll long long
#define MAXN 200010
#define INF 0x3f3f3f3f
#include <bits/stdc++.h>
using namespace std;

int main(){
#ifdef _DEBUG
    freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
#endif
#define int ll
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;
    cout << ceil(log2(n + 1)) << '\n';

    return 0;
}