#include "include\BigNumber.h"
#include <fstream>
using namespace std;
ifstream f("nunta.in");
int n;

int main() {
    f >> n;

    if(n <= 2) printf("%d\n", n);
    else
    {
        BigNumber A(1, 1);
        BigNumber B(1, 2);
        BigNumber C;
        for(int i = 3; i <= n; ++i) {
            C = A + B;
            A = B;
            B = C;
        }
        C.write_Data();
    }
}