优化：滚动数组

#include <bits/stdc++.h>
using namespace std;
const int N = 1e3 + 10;
const int mod = 1e9 + 7;
const int INF = 0x3f3f3f3f;
const long long LLINF = 0x3f3f3f3f3f3f3f3fLL;
int n, m, w[N], c[N], dp[N];
int main(){
	cin >> m >> n;
	for(int i = 1 ; i <= n ; i++){
		cin >> w[i] >> c[i];
	}
	for(int i = 1 ; i <= n ; i++){
		for(int j = m ; j >= w[i] ; j--){
			dp[j] = max(dp[j], dp[j - w[i]] + c[i]);
		}
	}
	cout << dp[m] << endl;
	return 0;
}