Fibonacci.cpp

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

typedef long long ll;

ll fib(unsigned n)
{
    int res[2] = {0, 1};
    if (n < 2)
        return res[n];
    ll fib1 = 0;
    ll fib2 = 1;
    ll fibN = 0;
    for (int i = 2; i <= n; i++)
    {
        fibN = (fib1 + fib2) % 1000000007;
        fib1 = fib2;
        fib2 = fibN;
    }
    return fibN;
}

int main()
{
    int n;
    while (scanf("%d", &n))
    {
        printf("%lld\n", fib(n));
    }
}