#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = int(a); i < int(b); i++)
#define RFOR(i, a, b) for(int i = int(a) - 1; i >= int(b); i--)



#define SZ(a) int(a.size())
#define ALL(a) a.begin() a.end()
#define PB push_back

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef long double db;

const db EPS = 1e-8;

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	int n, t;
	cin >> n >> t;
	VI d(n), s(n);
	FOR (i, 0, n) cin >> d[i] >> s[i];
	db l = -1e7, r = 1e7;
	FOR (it, 0, 147)
	{
		db m = (l + r) / 2;
		db time = 0;
		bool ok = 1;
		FOR (i, 0, n)
		{
			db sp = s[i] + m;
			if (sp < EPS)
			{
				ok = 0;
				break;
			}
			time += db(d[i]) / sp;
		}
		if (!ok || time > t)
			l = m;
		else
			r = m;
	}
	cout << fixed << setprecision(17) << l << '\n';
}