#include<bits/stdc++.h>
using namespace std;
int n,m,dp[1005][1005],w[1005],val[1005];
int dfs(int i,int j)
{
    if(dp[i][j] != -1) 
		return dp[i][j];
    int res;
    if(i == n) 
		res = 0;
    else if(j < w[i]) 
		res = dfs(i-1, j);
    else
		 res = max(dfs(i-1, j), dfs(i-1, j-w[i])+val[i]);
    return dp[i][j] = res;

}
int main()
{
	memset(dp,-1,sizeof(dp));
	cin>>m>>n;
	for(int i=1;i<=n;i++)
		cin>>w[i]>>val[i];
	int maxi=-1e9;
	for(int i=1;i<=n;i++)
		maxi=max(dfs(n,i),maxi);
		
	cout<<maxi;
	return 0;
}