#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int n,G,i,ma,j,gr[10001], p[10001], b[10001];
int main()
{
    f>>n>>G;
    for(i=1;i<=n;++i)
        f>>gr[i]>>p[i];
    b[gr[1]]=p[1];
    for(i=2;i<=n;++i)
    {
        for(j=G-gr[i];j>=1;--j)
            if(b[j]>0)
            if(b[gr[i]+j] <b[j]+p[i])
            b[gr[i]+j]=b[j]+p[i];
        if(b[gr[i]]<p[i])
            b[gr[i]]=p[i];
    }
ma=0;
    for(i=G;i>=1;--i)
        if(b[i]>ma)
        ma=b[i];
    if(ma<G)
        g<<-1;
    else
    g<<ma;
return 0;
}