#include<cstdio>
using namespace std;
int v[10000001];
int main()
{
    FILE *in, *out;
    in=fopen("energii.in", "r");
    out=fopen("energii.out", "w");
    int n, s, i, g, p, j;
    fscanf(in, "%d%d", &n, &s);
    v[0]=1;
    int smax=0, max=-1;
    for(i=1; i<=n; i++)
    {
        fscanf(in, "%d%d", &g, &p);
        for(j=smax; j>=0; j--)
            if(v[j]&&v[j+g]<v[j]+p)
            {
                v[j+g]=v[j]+p;
                if(v[j]+p>max)
                    max=v[i]+p;
                if(j+g>smax)
                    smax=i+g;
            }
    }
    fprintf(out, "%d", max);
    fclose(in);
    fclose(out);
    return 0;
}