#include<bits/stdc++.h>
#define MAXN 10005
using namespace std;
int dp[MAXN][MAXN];
int w[MAXN],v[MAXN];
int t,n;
int dfs(int i,int j)
{
    if(i>n||i<0||j>t||j<0) return 0;
    if(dp[i][j]!=0) return dp[i][j];
    if(j>w[i])
    {
        dp[i][j]=max(dp[i-1][j],dp[i-1][j-w[i]]+v[i]);
    }
    else dp[i][j]=dp[i-1][j];
    return dp[i][j];
}
int main()
{
    while(cin>>t>>n)
    {
        memset(dp,0,sizeof(dp));
        for(int i=1;i<=n;i++)
        {
            cin>>w[i]
            >>v[i];
        }
        dfs(n,t);
        cout<<dp[n][t]<<endl;
    }
    return 0;
}