https://old.ynoip.cn/p/3002

#include <cstdio>
using namespace std;
long long map[55][55];

int main(void) {
	for (int i = 1; i <= 50; i++)
		map[1][i] = 1;
	for (int i = 1; i <= 50; i++)
		map[i][1] = 1;
	for (int i = 2; i <= 50; i++)
		for (int u = 2; u <= 50; u++)
			map[i][u] = map[i - 1][u] + map[i][u - 1];
	int x, y;
	scanf("%d%d", &x, &y);
	printf("%lld ", map[x][y]);

	return 0;
}