BOJ_11442.cpp

#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define ll long long
#define ull unsigned long long
#define  pii pair<int,int>
#define MOD 1000000000
const ll INF = 10e12 + 10;
using namespace std;
typedef vector<vector<long long> > matrix;
const long long mod = 1000000007LL;

matrix operator *(const matrix &a, const matrix &b) {
    int n = a.size();
    matrix c(n, vector<long long>(n));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            for (int k = 0; k < n; k++) {
                c[i][j] += a[i][k] * b[k][j];
            }
            c[i][j] %= mod;
        }
    }
    return c;
}

int main() {
    ios_base::sync_with_stdio(false), cin.tie(0);
    long long n;
    cin >> n;
    if (n % 2)n++;
    if (n <= 1) {
        cout << n << '\n';
        return 0;
    }

    matrix ans = {{1, 0}, {0, 1}};
    matrix a = {{1, 1}, {1, 0}};

    while (n > 0) {
        if (n % 2 == 1) {
            ans = ans * a;
        }
        a = a * a;
        n /= 2;
    }

    cout << ans[0][1] << '\n';
}