4和9号测试点错误，有没有大佬帮帮忙

#include <bits/stdc++.h>
using namespace std;
int f[110][1010], c[110], v[1010];

int maxn(int a, int b){
	if(a > b) return a;
	else return b;
}

int main(){
	int n, m, ans;
	cin >> m >> n;
	for(int i = 1; i <= n; i++){
		cin >> c[i] >> v[i];
	}
	
	for(int i = 1; i <= n; i++){
		for(int j = m; j >= 0; j--){
			if(j - c[i] >= 0){
				f[i][j] = maxn(f[i-1][j], f[i-1][j-c[i]] + v[i]);	
			}
			else f[i][j] = f[i-1][j];
			ans = maxn(ans, f[i][j]);
		}
	}
	cout << ans << endl;
	return 0;
}