#include <iostream>
#include <cstdio>

using namespace std;

struct generator
{
    int e;
    int c;
};

generator v[1005];

int suma[10005],minim=2e9;

int main()
{
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    int n,w,maxim=0,MAX=0,i,j;
    cin>>n>>w;
    for(i=1;i<=n;i++)
        cin>>v[i].e>>v[i].c;
    for(i=1;i<=10002;i++)
        suma[i]=2e9;
    for(i=1;i<=n;i++)
    {
        for(j=maxim;j>=0;j--)
            if( suma[j]+v[i].c<suma[j+v[i].e])
                suma[j+v[i].e]=suma[j]+v[i].c;
        if(suma[j]+v[i].e>maxim)
            maxim=suma[j]+v[i].e;
    }
    for(i=w;i<=10002;i++)
        if(suma[i]<minim)
            minim=suma[i];
    cout<<minim;
    return 0;
}