#include <bits/stdc++.h>
#define DEBUG
using namespace std;
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    long long k, n, a, b;
    cin >> k >> n;
    cout << 42 << "\n";
    vector<pair <long long, long long>> mp(n, {0, 0});
    long long count = 0;
    for(int i = 0; i < n; i++) {
        cin >> mp[i].first >> mp[i].second;
    }
    sort(mp.begin(), mp.end());
    for(int i = 0; i < mp.size(); i++) {
        if(mp[i].first * mp[i].second <= k) {
            count += mp[i].second;
            k -= mp[i].second * mp[i].first;
        }
        else {
            int a = 0;
            for(int j = mp[i].second; j * mp[i].first > k; i--) {
                a = i;
            }
            a--;
            count += a;
            k -= mp[i].first * a;
        }
    }
    cout << count;
    return 0;
}