#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define ll long long
#define x first
#define y second
#define pii pair<int, int>
#define int long long
#define ld long double
#define lsb(x) ((x) & (-(x)))
    
using namespace std;
    
mt19937 gen(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());
uniform_int_distribution<int> rng;
normal_distribution <double> rng_d(-1, 1);

pii v[1005];

void solve() {
    int t, n;
    cin >> n >> t;

    int mn = 1e9;
    for(int i = 1; i <= n; i++) {
        cin >> v[i].x >> v[i].y;
        mn = min(mn, v[i].y);
    }

    ld st = -mn + 1e-7, dr = 1e9, mid;
    while(dr - st > 1e-7) {
        mid = (st + dr) / 2;
        
        ld tot = 0;
        for(int i = 1; i <= n; i++)
            tot += 1.0 * v[i].x / (mid + v[i].y);

        if(tot < t)
            dr = mid;
        else
            st = mid;
    }
    cout << fixed << setprecision(10) << st;
}
    
signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    
#ifndef ONLINE_JUDGE
    freopen("test.in", "r", stdin);
    freopen("test.out", "w", stdout);
#else
    
#endif
    
    int T = 1;
    
    //cin >> T;
    
    while(T--)
        solve();
    return 0;
}