#include <bits/stdc++.h>

using namespace std;

#define int long long
#define vi vector <int>
#define all(v) v.begin(), v.end()
#define pii pair <int, int>
#define mp(a, b) make_pair(a, b)
#define forn(i, from, n) for (int i = (int)(from); i < (int)(n); ++i)

const int INF = 1e18 + 9;

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

#ifdef LOCAL
    freopen("in", "r", stdin);
    freopen("out", "w", stdout);
#else
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif

    int n, k, t;
    cin >> n >> k >> t;
    vi v(n);
    forn(i, 0, n){
        int a, b;
        scanf("%lld-%lld", &a, &b);
        v[i] = a * b;
    }
    sort(all(v));
    forn(i, 1, n)
        v[i] += v[i - 1];
    forn(i, 0, n){
        if (v[i] / k + (v[i] % k > 0) >= t){
            cout << i + ((v[i] / k + v[i] % k) <= t);
            return 0;
        }
    }
    cout << n;
    return 0;
}