#include <fstream>
using namespace std;
ifstream fin("energii.in");
ofstream gout("energii.out");
int d[1001][5001],e[1001],c[1001];
int main()
{
    int n,g,i,j;
    fin>>n>>g;
    for(i=1;i<=n;i++)
    {
        fin>>e[i]>>c[i];
        if(e[i]<=g) d[i][e[i]]=c[i];
    }
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=g;j++)
        {
            if(d[i-1][j] && d[i-1][j]<d[i][j]) d[i][j]=d[i-1][j];
            if(j>=e[i] && d[i-1][j-e[i]] && (d[i-1][j-e[i]]+c[i]<d[i][j] || !d[i][j])) d[i][j]=d[i-1][j-e[i]]+c[i];
            else if(j<e[i] && (c[i]<d[i][j] || !d[i][j])) d[i][j]=c[i];

        }
    }
    if(!d[n][g]) gout<<-1;
    else gout<<d[n][g];
}