#include <bits/stdc++.h> #include <algorithm> using namespace std; const int N = 20; int stack[N][N]; int main() { int num; cin >> num; for (int i = 0; i <= num; i++) { stack[i][0]=1; } for (int i = 1; i <= num; i++) { for (int j = 1; i <= i; j++) { if(i == j) { stack[i][j] = stack[i][j - 1]; } else { stack[i][j] = stack[i-1][j] + stack[i][j -1]; } } } cout << stack[num][num]; return 0; }