#include <iostream>
#include <fstream>
#define nmax 5005
#define inf 10005

using namespace std;

ifstream f("energii.in");
ofstream g("energii.out");

int i,j,n,G,sol;
int v[nmax],w[nmax],m[inf];

int main()
{
    f>>n>>G;
    for(i=1; i<=n; i=i+1)
    {
        f>>w[i];
        f>>v[i];
    }
    for(i=0; i<=G; i=i+1)
        m[i]=20000;
    for(i=1; i<=n; i++)
        for(j=G; j>=0; j--)
            if(w[i]<j)
                m[j]=min(m[j],m[j-w[i]]+v[i]);
            else
                m[j]=min(m[j],v[i]);
    if(m[G]!=20000)
        g<<m[G];
    else
        g<<-1;
    return 0;
}