#include <bits/stdc++.h>
using namespace std;
 
int res = 0;
 
void bt(int n, int pos, int open, int val){
    if(pos == 2 * n) {
        if(val == 0) res++;
        return;
    } if(val - 1 >= 0) bt(n, pos + 1, open, val - 1);
    if(open < n) bt(n, pos + 1, open + 1, val + 1);    
}
 
void solve(){
    int n; cin >> n;
    bt(n, 1, 1, 1);
    cout << res << "\n";
}
 
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    solve();
}

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