#include <bits/stdc++.h>

using namespace std;

int main()
{
    double a, b, c;
    cin >> a >> b >> c;
    if(b == 0 && c == 0){
        cout << 0;
        return 0;
    }
    else if(c == 0){
        cout << a;
        return 0;
    }
    else if(b == 0){
        cout << 0;
        return 0;
    }
    vector <double> v;
    for(int i = 0; i < a; i++){
        double x, y;
        char c;
        cin >> x >> c >> y;
        double u = x * y;
        v.push_back(u);
    }
    double cnt = 0;
    sort(v.begin(), v.end());
    double t = b * c;
    for(int i = 0; i < v.size(); i++){
        double r = v[i];
        if(t - r > 0){
            t -= r;
            cnt++;
        }
    }
    cout << cnt;
    return 0;
}