#include <iostream>
#include <fstream>
#define DN 1005
#include <algorithm>
using namespace std;
ifstream in ("energii.in");
ofstream out ("energii.out");
pair <int,int> v[DN];

int main()
{
    int n,w, sum=0,val=0;
    in>>n>>w;
    for (int i=1;i<=n;i++)
    {
        in>>v[i].first>>v[i].second;
        sum+=v[i].second;
    }
    if (sum<w)
        {
            cout << "-1";
            return 0;
        }
    sort(v+1,v+n+1);
    int mini=-10000000;
    for(int i=1;i<=n;i++)
            for (int h=n;h>=1;h--)
                {
                    sum=0;
                    val=0;
                    for(int t=i;t<=h;t++)
                        {
                            val+=v[t].first;
                            sum+=v[t].second;
                        }
                    if (sum>=w)
                        mini=min(mini,val);
                }
    out<<mini;
    return 0;
}