#include <cstdio>
#include <fstream>
#include <cstring>

using namespace std;

FILE *fin = fopen("nunta.in", "r");
FILE *fout = fopen("nunta.out", "w");

const int NMax = 200;

int n;
int A[NMax], B[NMax], C[NMax];

void sum(){
    int i, t = 0;
    for(i = 1; i <= A[0] || i <= B[0] || t; i++){
        t += A[i] + B[i];
        C[i] = t % 10;
        t /= 10;
    }
    C[0] = i - 1;
}

void solve(){
    A[0] = B[0] = A[1] = B[1] = 1;
    for(int i = 1; i < n; i++){
        sum();
        for(int j = 0; j <= B[0]; j++){
            A[j] = B[j];
        }
        for(int j = 0; j <= C[0]; j++){
            B[j] = C[j];
        }
    }
    for(int i = C[0]; i > 0; i--){
        fprintf(fout, "%d", C[i]);
    }
}

int main(){
    fscanf(fin, "%d", &n);
    solve();
    return 0;
}