#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++)
    {
        int sum=1;
        for (int j=i-2; j>=0; j--)
            sum+=v[j];
        v[i]+=sum;
    }
}
int main()
{
    int n;
    erath();
    cin >> n;
    cout << v[n];
    return 0;
}