#include<bits/stdc++.h>
using namespace std;
const int N = 1000 + 10;
int m , w[N] , c[N] , dp[1010] , 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 = w[i];j >= m;j++) 
        	dp[j] = max(dp[j] , dp[j - w[i]] + c[i]);
	cout << dp[m];
	return 0;
}

#include <iostream> 
#include <stdio.h>
using namespace std;
const int N=1e6+10;
int m,n;
int 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=w[i];j<=m;j++){
			dp[j]=max(dp[j],dp[j-w[i]]+c[i]);
		}
	}
	cout<<dp[m];
	return 0;
}

#include <cstdio>
 
#include <algorithm>
 
#include <cstring>
 
#include <iostream>
 
using namespace std;
 
int w[100100],c[100100];
 
int f[100100];
 
int n,v;
 
int complete()
 
{
 
    for(int i=1;i<=n;i++)
 
        for(int j=w[i];j<=v;j++)
 
            f[j]=max(f[j],f[j-w[i]]+c[i]);
 
    return f[v];
 
}
 
int main()
 
{
 
    cin>>v>>n;
 
    for(int i=1;i<=n;i++)
 
        cin>>w[i]>>c[i];
 
    cout<<complete()<<endl;
 
    return 0;
 
}