#include<iostream>
#define MAX 16
using namespace std;
int dp[MAX];

int main(){
    int n;
    cin >> n;
    dp[0] = 1; dp[1] = 1;
    for(int i = 2; i <= n; i++){
        dp[i] = dp[i-1] + dp[i-2];
    }
    cout << dp[n] << endl;
    return 0;
}