#include <bits/stdc++.h>

using namespace std;
using LL = long long int;

const int MAX_N = 50005;

int N;
class Gift{
public:
  LL V, W;
  double value;
  void input()
  {
    cin >> V >> W;
    value = (double)V/(double)W;
  }

  bool operator < (const Gift& p) const {
    return value < p.value;
  }

  bool operator > (const Gift& p) const {
    return value > p.value;
  }
}G[MAX_N];
LL W;

LL ans = 0;
LL solve(int pos = 0, LL tmpV = 0, LL tmpW = 0)
{
  if((double)ans > tmpV + (double)(W-tmpW)*G[pos].value) {
    return tmpV;
  }

  if(pos == N) {
    ans = max(ans, tmpV);
    return tmpV;
  }

  LL ret = 0;
  if(tmpW + G[pos].W <= W) {
    ret = max(ret, solve(pos+1, tmpV+G[pos].V, tmpW+G[pos].W));
  }
  ret = max(ret, solve(pos+1, tmpV, tmpW));
  ans = max(ret, ans);
  return ret;
}

int main()
{
  cin >> N >> W;
  for(int i = 0; i < N; i++) {
    G[i].input();
  }

  sort(G, G+N, greater<Gift>());
  solve();
  cout << ans << endl;

  return 0;
}