#include <iostream>
#include <fstream>
using namespace std;
ifstream fin ("rucsac.in");
ofstream fout ("rucsac.out");
int n, gr[5010], co[5010], gmax;
long long x[15010], y[15010];

int main()
{
    int i, j=0;
    fin>>n>>gmax;
    for(i=1; i<=n; i++)
    {
        fin>>gr[i]>>co[i];
        if(i-gr[i]>0)
        {
            if(i%2==1)
            {
                if(y[i-gr[i]]+co[i]>y[i])
                    x[i]=y[i-gr[i]]+co[i];
                else
                    x[i]=y[i];
            }
            else
            {
                if(x[i-gr[i]]+co[i]>x[i])
                    y[i]=x[i-gr[i]]+co[i];
                else
                    y[i]=x[i];
            }

        }
    }

    for(j=2; j<=n; j++)
    {
       for(i=1; i<=gmax; i++)
        {
            if(i-gr[j]>0)
            {
                if(j%2==1)
                {
                    if(y[i-gr[j]]+co[j]>y[i])
                        x[i]=y[i-gr[j]]+co[j];
                    else
                        x[i]=y[i];
                }
                else
                {
                    if(x[i-gr[j]]+co[j]>x[i])
                        y[i]=x[i-gr[j]]+co[j];
                    else
                        y[i]=x[i];
                }

            }
            else
                if(j%2==1)
                    x[i]=y[i];
                else
                    y[i]=x[i];
        }
    }

    if(n%2==1) fout<<x[gmax];
    else fout<<y[gmax];

    fin.close();
    fout.close();
    return 0;
}