#include<bits/stdc++.h>
#define int long long
#define pir pair<int,int>
#define pb push_back
#define fi first
#define se second
using namespace std;
void chkmax(int &a,int b){a=max(a,b);}
void chkmin(int &a,int b){a=min(a,b);}
inline int re()
{
    char c=getchar();
    int x=0,f=1;
    while(c<'0'||c>'9'){if(c=='-') f=-1;c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
    return x*f;
}
const int N=500010,INF=0x3f3f3f3f3f3f3f3f;
int n,m;
pir d[N];
bool cmp(int x,int y){return x>y;}
namespace case1
{
    const int M=10010;
    int f[2][M];
    void solve()
    {
        for(int i=1;i<=m;i++) f[0][i]=-INF;
        f[0][0]=0;
        for(int i=1;i<=n;i++)
        {
            int bi=i&1;
            for(int j=0;j<=m;j++) f[bi][j]=-INF;
            for(int j=0;j<=m;j++)
            {
                f[bi][j]=f[bi^1][j];
                if(j>=d[i].se) chkmax(f[bi][j],f[bi^1][j-d[i].se]+d[i].fi);
            }
        }
        int ans=-INF;
        for(int i=0;i<=m;i++) chkmax(ans,f[n&1][i]);
        printf("%lld\n",ans);
        return;
    }
}
signed main()
{
    freopen("Mining.in","r",stdin);
    freopen("Mining.out","w",stdout);
    n=re();m=re();
    int num1=-1,num2=-1,num3=-1;
    for(int i=1;i<=n;i++)
    {
        d[i].fi=re();d[i].se=re();
        if(num1==-1) num1=d[i].se;
        else if(num1!=d[i].se)
        {
            if(num2==-1) num2=d[i].se;
            else if(num2!=d[i].se) num3=0;
        }
    }
    if(num3==0) case1::solve();
    else if(num2==-1)
    {
        vector<int> vec;vec.clear();
        for(int i=1;i<=n;i++) vec.pb(d[i].fi);
        sort(vec.begin(),vec.end(),cmp);
        vec.resize(N);
        for(int i=1;i<=n;i++) vec[i]+=vec[i-1];
        int pos=m/num1;chkmin(pos,n);
        printf("%lld\n",pos==0?0:vec[pos-1]);
        return 0;
    }
    else if(num2!=-1)
    {
        vector<int> v1,v2;v1.clear();v2.clear();
        for(int i=1;i<=n;i++) if(d[i].se==num1) v1.pb(d[i].fi);else v2.pb(d[i].fi);
        sort(v1.begin(),v1.end(),cmp);sort(v2.begin(),v2.end(),cmp);
        v1.resize(N);v2.resize(N);
        for(int i=1;i<=n;i++) v1[i]+=v1[i-1];
        for(int i=1;i<=n;i++) v2[i]+=v2[i-1];
        int ans=-INF;
        for(int i=0;i<=n;i++)
        {
            int now=i*num1;
            if(now>m) break;
            int pos=(m-now)/num2;chkmin(pos,n);
            chkmax(ans,(i==0?0:v1[i-1])+(pos==0?0:v2[pos-1]));
        }
        printf("%lld\n",ans);
        return 0;
    }
}