#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<pair<long long, long long>> p(n);
    for (int i = 0; i < n; i++) {
        cin >> p[i].second >> p[i].first;
        p[i].second *= -1;
    }
    sort(p.begin(), p.end());
    for (int i = 0; i < n; i++) {
        p[i].second *= -1;
        swap(p[i].first, p[i].second);
    }
    auto [in, out] = p[0];
    int ans = 0;
    for (int i = 1; i < n; i++) {
        auto [l, r] = p[i];
        if (out <= l) {
            out = r;
        } else {
            ans++;
            long long q = (out % l == 0 ? out / l : out / l + 1);
            out = r * q;
        }
    }
    cout << ans << endl;
}