#include <fstream>
#include <string.h>
using namespace std;
ifstream cin("nunta.in");
ofstream cout("nunta.out");
long long int v[1001];
void erath()
{
    v[0]=v[1]=1;
    for (int i=2; i<=1000; i++)
    {
        v[i]=v[i-1]+v[i-2];
    }
}
int main()
{
    int n;
    erath();
    cin >> n;
    cout << v[n];
    return 0;
}