#include <iostream>
using namespace std;
const int N = 110;
int t, n;
int v[N], w[N];
int f[N][N * 10];
int main() {
cin >> t >> n;
for (int i = 1; i <= n; i ++ ) cin >> v[i] >> w[i];
for (int i = 1; i <= n; i ++ ) {
for (int j = 1; j <= t; j ++ ) {
f[i][j] = f[i - 1][j];
if (j >= v[i]) f[i][j] = max(f[i][j], f[i - 1][j - v[i]] + w[i]);
}
}
cout << f[n][t] << endl;
return 0;
}