#include <bits/stdc++.h>
using namespace std;
long long n, p, a[100001], b[100001];
bool check(long double t) {
  long double pwr = p;
  for (long long i = 1; i <= n; i++) {
    if (1.0 * b[i] - 1.0 * a[i] * t > 0) continue;
    pwr -= 1.0 * a[i] - 1.0 * b[i] / t;
  }
  return pwr >= 0;
}
signed main() {
  cin.tie(0);
  cout.tie(0);
  ios_base::sync_with_stdio(false);
  cin >> n >> p;
  for (long long i = 1; i <= n; i++) {
    cin >> a[i] >> b[i];
  }
  long double l = 0, r = 1e13;
  long double ans = -1;
  while (r - l > 1e-6) {
    long double mid = (l + r) * 0.5;
    if (!check(mid)) {
      ans = mid;
      r = mid;
    } else
      l = mid;
  }
  cout << fixed << setprecision(15) << ans << '\n';
}
