#include <bits/stdc++.h>
using namespace std;
int s[100][100];
int main() {
  int n, i, j;
  scanf("%d", &n);
  for (i = 1; i <= n; i++) {
    for (j = 1; j <= n; j++) {
      if (i == 1)
        s[i][j] = 1;
      else
        s[i][j] = s[i - 1][j] + s[i][j - 1];
    }
  }
  int max = 0;
  for (i = 1; i <= n; i++) {
    for (j = 1; j <= n; j++) {
      if (s[i][j] > max) max = s[i][j];
    }
  }
  printf("%d", max);
}
