void main(){
  import std.stdio, std.string, std.conv, std.algorithm;
  import std.typecons;

  int n; long wmax; rd(n, wmax);
  auto v=new long[](n), w=new long[](n);
  foreach(i; 0..n) rd(v[i], w[i]);

  size_t B=50000;
  alias T=Tuple!(long, "vsum", long, "wsum");
  T[] cur; cur~=T(0, 0);
  foreach(i; 0..n){
    T[] nex;
    foreach(e; cur){
      nex~=e;
      if(e.wsum+w[i]<=wmax) nex~=T(e.vsum+v[i], e.wsum+w[i]);
    }
    sort!((x, y)=>(x.vsum>y.vsum))(nex);
    if(nex.length>B) cur=nex[0..B];
    else cur=nex;
  }

  writeln(cur[0].vsum);
}

void rd(T...)(ref T x){
  import std.stdio, std.string, std.conv;
  auto l=readln.split;
  assert(l.length==x.length);
  foreach(i, ref e; x){
    e=l[i].to!(typeof(e));
  }
}
void wr(T...)(T x){
  import std.stdio;
  foreach(e; x) stderr.write(e, " ");
  stderr.writeln();
}