#include <fstream>

using namespace std;
ifstream in("rucsac.in");
ofstream out("rucsac.out");
int g[10005],p[10005];
int main()
{
    long long n,G,gtotal=0,stotal=0;
    in>>n>>G;
    for(int i=1;i<=n;i++)
    {
        in>>g[i]>>p[i];
        gtotal=gtotal+g[i];
        stotal=stotal+p[i];
    }
    gtotal-=G;
    for(int i=1;i<n;i++)
        for(int j=i+1;j<=n;j++)
    {
        if(p[i]>p[j])
        {
            swap(p[i],p[j]);
            swap(g[i],g[j]);
        }
    }

        for(int i=1;i<=n;i++)
        {
            if(gtotal>0)
            {
                gtotal-=g[i];
                stotal-=p[i];
            }

        }
        out<<stotal;
    return 0;
}