#include <cstdio> int n, f[30]; int main() { scanf("%d", &n); f[0] = 1, f[1] = 1; for(int i=2; i<=n; i++) for(int j=0; j<i; j++) f[i] += f[j] * f[i-j-1]; printf("%d", f[n]); return 0; }