#include <iostream>
#include <cmath>
using namespace std;
int main()
{
int n, a, b;
cin >> n >> a >> b;
for (int i = 0; i < n; i++)
{
int d, h;
cin >> d >> h;
b -= ((h + a - 1) / a - 1) * d;
if (b <= 0)
{
cout << "No\n";
return 0;
}
}
cout << "Yes\n";
return 0;
}
