#include <fstream>
using namespace std;
   
int e[15000],c[15000],v[15000];
int s,i,j,n,sum,g,sol=100000;
ifstream in("energii.in");
ofstream out("energii.out");
 
int main(){
    in>>n>>g;
    for (i=1;i<=n;i++){
        in>>e[i]>>c[i];
        if (s<e[i]) s=e[i];
        sum+=e[i];
    }
    if (sum<g) out<<"-1";
    else{
        for(i=1;i<=g+s;i++)
        v[i]=100000;
        v[0]=0;
        for (i=1;i<=n;i++)
        for (j=g-1;j>=0;j--)
        if ((v[j]!=100000)&&(v[j+e[i]]>v[j]+c[i])) v[j+e[i]]=v[j]+c[i];
        for (i=g;i<=g+s;i++)
        if(v[i]<sol) sol=v[i];
        out<<sol;
        }
}