#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
int main()
{
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
ll l, n;
cin >> l >> n;
vector<pll> persons(n);
for (ll i = 0; i < n; i++)
cin >> persons[i].first >> persons[i].second;
sort(persons.begin(), persons.end());
//lis
multiset<ll> lis;
for (ll i = 0; i < n; i++)
{
ll val = l / persons[i].second + persons[i].first;
auto it = lis.lower_bound(val);
if (it != lis.begin())
lis.erase(--it);
lis.insert(val);
}
cout << lis.size();
return 0;
}
