#include <bits/stdc++.h>
using namespace std;
ifstream in("kfib.in");
ofstream out("kfib.out");
void multiply(long long F[2][2], long long M[2][2])
{
    long long x =  F[0][0] * M[0][0] + F[0][1] * M[1][0];
    long long y =  F[0][0] * M[0][1] + F[0][1] * M[1][1];
    long long z =  F[1][0] * M[0][0] + F[1][1] * M[1][0];
    long long w =  F[1][0] * M[0][1] + F[1][1] * M[1][1];
    F[0][0] = x;
    F[0][1] = y;
    F[1][0] = z;
    F[1][1] = w;
}
void power(long long F[2][2], int n)
{
    if (n == 0 || n == 1)
        return;
    long long M[2][2] = {{1,1},{1,0}};
    power(F, n / 2);
    multiply(F, F);
    if (n % 2 != 0)
        multiply(F, M);
}

long long fibo_matrix(long long n)
{
    long long F[2][2] = {{1,1},{1,0}};
    if (n == 0)
        return 0;
    power(F, n - 1);
    return F[0][0];
}
int main()
{
    int n;
        in >> n;
        out << fibo_matrix(n);
    return 0;
}