#include <fstream>
#include <iostream>
using namespace std;
int a[100],Gmax,v[100],g[100],i,n,j,s,k;
int main()
{
ifstream f( "energii.in");
ofstream h( "energii.out");
f>>n>>Gmax;
cout<<n<<endl;
for(i=1;i<=n;i++)
{f>>g[i]>>v[i];
s=s+g[i];}
if( s<Gmax) h<<-1;
else
{
    for(i=1;i<=Gmax;i++)a[i]=10002;

for (i=1;i<=n;i++)
{
    for(j=Gmax;j>=0;j--)
if(g[i]>=j)
{
    if(a[j]>v[i]) a[j]=v[i];
}
else
if(v[i]+a[j-g[i]]<a[j])
a[j]=v[i]+a[j-g[i]];
}}
h<<a[Gmax];}