#include <iostream>
#include <fstream>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int i,j,n,nec;
long sum,cs;
int main()
{
    f>>n>>nec;
    int* e=new int[n+5];
    int* c=new int[n+5];
    for(i=1;i<=n;i++)
        f>>e[i]>>c[i];
    for(i=1;i<=n;i++)
    {
        if(sum==nec)
            break;
        if(i==1)
            {
                sum=e[i];
                cs=c[i];
            }
            else
            {
                if(sum>=e[i])
                {
                    sum=sum+e[i];
                    cs=cs+c[i];
                }
                else
                    if(sum<e[i])
                    {
                        sum=e[i];
                        cs=c[i];
                    }
            }
    }
    g<<cs;
}