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