#include <iostream>

using namespace std;

typedef long long ll;

ll n, m, k;
ll a[30001], b[30001];
bool flag = false;

int main() {
	cin >> k >> m >> n;
    for (ll i = 1; i <= m; i ++ ) cin >> a[i] >> b[i];
    for (ll i = 1; i <= n; i ++ ) if (k / a[i] * b[i] >= n) {
            cout << i << endl;
            flag = true;
        }
    if (!flag) cout << -1 << endl;
    return 0;
}