#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef int _loop_int;
#define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i)
#define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i)
#define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define CHMIN(a,b) a=min((a),(b))
#define CHMAX(a,b) a=max((a),(b))

// mod
const ll MOD = 1000000007ll;
#define FIX(a) ((a)%MOD+MOD)%MOD

// floating
typedef double Real;
const Real EPS = 1e-11;
#define EQ0(x) (abs(x)<EPS)
#define EQ(a,b) (abs(a-b)<EPS)
typedef complex<Real> P;

#define sz 19

int n;
ll W;
ll v[5252], w[5252];
ll dp[1<<sz];

int main(){
  scanf("%d%lld",&n,&W);
  REP(i,n)scanf("%lld%lld",v+i,w+i);
  int Wbit = 0;
  {
    ll tmp = W;
    while(tmp>0){
      tmp /= 2;
      Wbit++;
    }
  }
  int sh = max(0, Wbit - sz);
  int admsk = (1<<sh) - 1;
  REP(i,n){
    w[i] = (w[i]+admsk) >> sh;
  }
  W = W >> sh;
  REP(i,n){
    int ww = w[i];
    ll vv = v[i];
    FORR(j,0,W-ww+1){
      CHMAX(dp[j+ww], dp[j]+vv);
    }
  }
  ll ans = 0;
  REP(i,W+1)CHMAX(ans,dp[i]);
  printf("%lld\n", ans);
  return 0;
}