#include <iostream>
#include <algorithm>
using namespace std;

int main() {
    int maxw, n;
    cin >> maxw >> n;
    
    int weight[105], value[105];
    for (int i = 1; i <= n; i++) {
        cin >> weight[i] >> value[i];
    }
    
    // dp[j] 表示背包容量为 j 时的最大价值
    int dp[20005] = {0};
    
    for (int i = 1; i <= n; i++) {
        // 从大到小遍历，保证每个物品只选一次
        for (int j = maxw; j >= weight[i]; j--) {
            dp[j] = max(dp[j], dp[j - weight[i]] + value[i]);
        }
    }
    
    cout << dp[maxw] << endl;
    
    return 0;
}