#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const double eps = 1e-7;
const double INF = 100000000.00000000;
const int MAXN = 1010;
int n;

double t, d[MAXN], s[MAXN];

int main() {
	scanf("%d %lf", &n, &t);
	double l = -INF, r = INF;
	for (int i = 1; i <= n; i++) {
		scanf("%lf %lf", &d[i], &s[i]);
		l = max(l, -s[i]);
	}
	while ((r - l) > eps) {
		//printf("%lf %lf\n", l, r);
		double mid = (r + l) / (2.00000000);
		double ans = 0;
		for (int i = 1; i <= n; i++) {
			ans += d[i] / (s[i] + mid);
		}
		if (ans > t) l = mid;
		else r = mid;
	}
	printf("%.10lf\n", l);
	return 0;
}