代码

#include <cstdio>int n;long long f[20];int main(){	int i;	scanf("%d", &n);	f[0] = 1;	for(i = 1; i <= n; i++) f[i] = f[i - 1] * (4 * i - 2) / (i + 1);	printf("%lld\n", f[n]);	return 0;}