#include<bits/stdc++.h>
#define N 500005
#define M 10005
#define int long long
#define db double
#define fo(i,l,r) for(int i=l;i<=r;i++)
#define rf(i,r,l) for(int i=r;i>=l;i--)
using namespace std;
int T,n,m,k,op,x,y,z,ans,last;
int f[M];
struct node{int v,m;bool operator<(node y){return m<y.m;}}a[N]; 
void swap(int &x,int &y){int t=x;x=y;y=t;}
int max(int x,int y){return x>y?x:y;}
int min(int x,int y){return x<y?x:y;}
void ckmax(int &x,int y){if(y>x)x=y;}
void ckmin(int &x,int y){if(y<x)x=y;}
int read(){
    int sum=0;bool f=0;char c=getchar();
    for(;c<48||c>57;c=getchar())if(c==45)f=1;
    for(;c>=48&&c<=57;c=getchar())sum=sum*10+(c&15);
    return f?-sum:sum;
}
bool cmp1(node x,node y){return x.v*y.m>y.v*x.m;}
bool cmp2(node x,node y){return x.m^y.m?x.m<y.m:x.v*y.m>y.v*x.m;}
signed main(){
    ios::sync_with_stdio(0);cin.tie(0);
    freopen("Mining.in","r",stdin);freopen("Mining.out","w",stdout);
    n=read();m=read();
    if(n<=1000&&m<=10000){
        while(n--){
            x=read();y=read();
            rf(i,m,y)ckmax(f[i],f[i-y]+x);
        }
        return !printf("%lld",f[m]);
    }
    fo(i,1,n)a[i]={read(),read()};
    sort(a+1,a+n+1);
    x=0;
    fo(i,2,n)if(a[i].m!=a[i-1].m)x++;
    if(x==1){
        sort(a+1,a+n+1,cmp2);
        int k=1,sum=0,as=0;
        while(a[k].m!=a[n].m)k++;
        fo(i,1,k-1)sum+=a[i].m,as+=a[i].v;
        for(int i=k-1,j=k;~i;i--){
            while(sum+a[j].m<=m)sum+=a[j].m,as+=a[j].v,j++;
            if(sum<=m)ckmax(ans,as);
            sum-=a[i].m;as-=a[i].v;
        }
        return !printf("%lld",ans);
    }
    sort(a+1,a+n+1,cmp1);
    fo(i,1,n)if(a[i].m<=m)m-=a[i].m,ans+=a[i].v;
    printf("%lld",ans);
    return 0;
}