Submission

Score: 100

User: un8qe_x3

Problemset: Fibonacci Croissant

Language: cpp

Time: 0.002 second

Submitted On: 2025-11-16 14:03:13

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

unsigned long long fib(const int n) {
    if (n == 0) return 0;
    unsigned long long a = 0, b = 1;
    for (int i = 2; i <= n; i++) {
        const unsigned long long c = a + b;
        a = b;
        b = c;
    }
    return b;
}

int main() {
    int a;
    cin >> a;
    cout << fib(a + 2) - 1;
}