#define _CRT_SECURE_NO_WARNINGS
#define debug(l) cerr<<#l<<' '<<l<<'\n';
#include "bits/stdc++.h"
using namespace std;
#define all(a) a.begin(), a.end()
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
struct Matrix {
    ll n, m;
    vector<vector<ll>> a;
    Matrix(ll _n, ll _m) {
        n = _n, m = _m;
        a.resize(n, vector<ll>(m,0));
    }
    Matrix(ll _n, ll _m, vector<vector<ll>> &b) {
        n = _n, m = _m;
        a.resize(n, vector<ll>(m,0));
        a = b;
    }
    void assign_ed() {
        for (ll i = 0; i < min(n, m); i++)a[i][i] = 1;
    }
    Matrix operator*(const Matrix& other) const {
        vector<vector<ll>> c(other.n, vector<ll>(other.m));
        for (ll k = 0; k < m; k++) {
            for (ll i = 0; i < other.n; i++) {
                for (ll j = 0; j < other.m; j++) {
                    c[i][j] += a[i][k] * other.a[k][j];
                }
            }
        }
        return Matrix(other.n, other.m, c);
    }
};
Matrix Fastpow(Matrix a, ll n) {
    Matrix res(a.n, a.m);
    res.assign_ed();
    while (n) {
        if (n & 1) {
            res = res * a;
        }
        a = a * a;
        n >>= 1;
    }
    return res;
}
signed main() {
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    Matrix Fib(2, 2),Vec_res(2,1);
    Fib.a[0][0] = 1;
    Fib.a[0][1] = 1;
    Fib.a[1][0] = 1;
    Fib.a[1][1] = 0;

    Vec_res.a[0][0] = 1;
    Vec_res.a[1][0] = 1;
    ll n;
    cin >> n;
    n--;
    Fib = Fastpow(Fib, n);
    Vec_res = Fib * Vec_res;
    cout << Vec_res.a[1][0];
}