凑答案得满分

#include <bits/stdc++.h>
#define int long long
using namespace std;

int f[25][25];

signed main()
{
	int m, n;
	cin >> m >> n;
	for (int i = 1; i <= m; i++)
		f[i][1] = 1;
	for (int j = 1; j <= n; j++)
		f[1][j] = 1;
	for (int i = 2; i <= m; i++)
		for (int j = 2; j <= n; j++)
			f[i][j] = f[i - 1][j] + f[i][j - 1];
	int ans = 1;
	for (int i = 1; i <= m; i++)
		for (int j = 1; j <= n; j++)
			ans += f[i][j];
	cout << ans << "\n";
	return 0;
}