#include <iostream>
#include <fstream>
#include <cstdio>
#include <cassert>
#include <complex>
#include <cmath>
#include <algorithm>
#include <vector>
#include <string>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <numeric>
#include <sstream>
#include <ctime>
#include <cctype>
#include <set>
#include <map>
#include <queue>
#include <bitset>
#include <deque>
#include <stack>
#include <memory.h>
using namespace std;
typedef long long ll;
#define mp make_pair
#define CLR(x) memset(x,0,sizeof x)
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define pii pair<int,int>
#define vi vector<int>
#define MAX 1000000000000000000
#define MOD 1000000007
#define PI 3.141592653589793238462
#define INF 0x3F3F3F3F
typedef long long ll;
using namespace std;
string i_s(int x){
	if(x==0)
	return "0";
	string ret="";
	while(x){
		ret=ret+(char)(x%10+'0');
		x/=10;
	}
	reverse(ret.begin(),ret.end());
	return ret;
}
string add(string a,string b){
	if(a=="")
	a="0";
	if(b=="")
	b="0";
	if(a.length()<b.length())
	swap(a,b);
	while(b.length()<a.length()){
		b='0'+b;
	}
	for(int i=0;i<a.length();i++){
		a[i]=a[i]+(b[i]-'0');
	}
	bool big=false;
	for(int i=a.length()-1;i>=0;i--){
		if(big){
			a[i]++;
		}
		big=false;
		if(a[i]>'9'){
			a[i]=a[i]-10;
			big=true;
		}
	}
	if(big)
	a='1'+a;
	return a;
}
string mul(string a,string b){
	vector<int> va,vb;
	if(a=="0" || b=="0")
	return "0";
	string ans;
	for(int i=0;i<a.length();i++){
		va.push_back(a[i]-'0');
	}
	for(int i=0;i<b.length();i++){
		vb.push_back(b[i]-'0');
	}
	reverse(va.begin(),va.end());
	reverse(vb.begin(),vb.end());
	vector<int> res;
	res.clear();
	res.resize(1005);
	for(int i=0;i<a.length();i++){
		for(int j=0;j<b.length();j++){
			res[i+j]+=(va[i]*vb[j]);
		}
	}
	for(int i=0;i<1005;i++){
		if(res[i]>9){
			res[i+1]+=(res[i]/10);
			res[i]%=10;
		}
	}
	for(int i=0;i<1005;i++){
		ans+=(res[i]+'0');
	}
	reverse(ans.begin(),ans.end());
	int k=0;
	while(ans[k]=='0'){
		k++;
	}
	ans=ans.substr(k);
	return ans;
}
bool is_prime(int n){
	if(n<2)
    return false;
    for(int i=2;i*i<=n;i++)
    if(n%i==0)
    return false;
    return true;
}
struct good
{
    int w,v;
}g[110];
 
bool cmp(good a,good b)
{
    return a.v > b.v;
}
good A[110],B[110],C[110],D[110];
 
ll swa[110],swb[110],swc[110],swd[110];
ll sva[110],svb[110],svc[110],svd[110];
 
int main(){
	//freopen("input.in","r",stdin);
	//freopen("output.out","w",stdout);
	int n,w,i,j,k,l;
    int a,b,c,d;
    while(scanf("%d%d",&n,&w)==2)
    {
        a = b = c = d = 0;
        for(i=1;i<=n;i++)
        {
            scanf("%d%d",&g[i].w,&g[i].v);
            if(g[i].w == g[1].w)
                A[++a] = g[i];
            if(g[i].w == g[1].w + 1)
                B[++b] = g[i];
            if(g[i].w == g[1].w + 2)
                C[++c] = g[i];
            if(g[i].w == g[1].w + 3)
                D[++d] = g[i];
        }
        sort(A+1,A+a+1,cmp);
        sort(B+1,B+b+1,cmp);
        sort(C+1,C+c+1,cmp);
        sort(D+1,D+d+1,cmp);
        swa[0] = swb[0] = swc[0] = swd[0] = 0;
        sva[0] = svb[0] = svc[0] = svd[0] = 0;
        for(i=1;i<=a;i++)
        {
            swa[i] = swa[i-1] + A[i].w;
            sva[i] = sva[i-1] + A[i].v;
        }
        for(i=1;i<=b;i++)
        {
            swb[i] = swb[i-1] + B[i].w;
            svb[i] = svb[i-1] + B[i].v;
        }
        for(i=1;i<=c;i++)
        {
            swc[i] = swc[i-1] + C[i].w;
            svc[i] = svc[i-1] + C[i].v;
        }
        for(i=1;i<=d;i++)
        {
            swd[i] = swd[i-1] + D[i].w;
            svd[i] = svd[i-1] + D[i].v;
        }
        int sumv = 0;
        int ans = 0;
        for(i=0;i<=a;i++)
        {
            for(j=0;j<=b;j++)
            {
                for(k=0;k<=c;k++)
                {
                    for(l=0;l<=d;l++)
                    {
                        ll sum = swa[i] + swb[j] + swc[k] + swd[l];
                        if(sum <= (ll)w)
                        {
                            ans = max((ll)ans,sva[i]+svb[j]+svc[k]+svd[l]);
                        }
                    }
                }
            }
        }
        cout << ans << endl;
    }
	//system("pause");
}

Measured memory_bytes: 256