509A.cpp

#include<bits/stdc++.h>
using namespace std;


#define ll long long
#define endl '\n'
#define debug(n) cout<<(n)<<endl;
const ll INF = 2e18 + 99;

int main(){
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);

  int n;
  cin>>n;

  int a[n][n];

  for(int i = 0; i < n; i++){
    for(int j = 0; j < n; j++){
      if(i == 0 || j == 0){
        a[i][j] = 1;
      }
      else{
        a[i][j] = a[i-1][j] + a[i][j-1];
      }
    }
  }
  cout<<a[n-1][n-1];
}