#include<bits/stdc++.h>
using namespace std;
#define N 35
#define M 250
int dp[M], w[N], c[N];
int main()
{
    int m, n;
    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];
    return 0;
}