求助，只会输出1，悲

题目https://www.luogu.com.cn/problem/P1644

#include "bits/stdc++.h"
using namespace std;
int n, m, f[25][25];

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