Submission

Score: 0

User: cyblox_boi

Problemset: Croissant Express

Language: cpp

Time: 0.003 second

Submitted On: 2026-01-01 02:00:25

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

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    long long f0 = 0, f1 = 1;
    long long sum = f0 + f1;

    if (n == 0)
    {
        cout << 0 << '\n';
        return 0;
    }

    for (int i = 2; i <= n; i++)
    {
        long long f2 = f0 + f1;
        sum += f2;
        f0 = f1;
        f1 = f2;
    }

    cout << sum << '\n';
    return 0;
}