和题解几乎一模一样，为什么会WA

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<string>
#include<queue>
#include<algorithm>
#include<map>
using namespace std;
#define ll long long
ll M,T,tot[1005],v[1005];
bool vs[1005][1005];
ll f[100000005];
ll DP_gundongshuzu(){
	for(ll i=1;i<=M;i++){
		for(ll j=tot[i];j<=T;j++){
				f[j]=max(f[j],f[j-tot[i]]+v[i])	;	
		}
	}
	return f[T];
} 
int main(){
//	freopen("未命名2333.in","r",stdin);
//	freopen("未命名2333.out","w",stdout);
	cin>>T>>M;	
	for(int i=1;i<=M;i++){
		cin>>tot[i]>>v[i];
	}
//	cout<<pusude_dfs(1,0);
//	cout<<DP_pusushuzu();
	cout<<DP_gundongshuzu();
//	fclose(stdin);
//	fclose(stdout);
	return 0;
}