import std.conv, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

void chmin(T)(ref T t, in T f) { if (t > f) t = f; }
void chmax(T)(ref T t, in T f) { if (t < f) t = f; }

int binarySearch(T)(in T[] as, in bool delegate(T) test) { int low = -1, upp = cast(int)(as.length); for (; low + 1 < upp; ) { int mid = (low + upp) >> 1; (test(as[mid]) ? low : upp) = mid; } return upp; }
int lowerBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a < val)); }
int upperBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a <= val)); }


int N;
long W;
Tuple!(long, "v", long, "w")[] P;

long[] sumV, sumW;

long greedy(int i, long x) {
  const j = sumW.upperBound(sumW[i] + x) - 1;
  assert(i <= j && j <= N);
  return sumV[j] - sumV[i];
}

long dfs(int i, long x) {
  if (i == N) {
    return 0;
  }
  long ret = 0;
  if (x >= P[i].w) {
    chmax(ret, P[i].v + dfs(i + 1, x - P[i].w));
  }
  if (ret < greedy(i + 1, x)) {
    chmax(ret, dfs(i + 1, x));
  }
  return ret;
}

void main() {
  try {
    for (; ; ) {
      N = readInt();
      W = readLong();
      P.length = N;
      foreach (i; 0 .. N) {
        P[i].v = readLong();
        P[i].w = readLong();
      }
      
      // a.v / a.w > b.v / b.w
      P.sort!((a, b) => ((a.v / a.w != b.v / b.w) ? (a.v / a.w > b.v / b.w) : (a.v % a.w * b.w > b.v % b.w * a.w)));
      
      sumV = new long[N + 1];
      sumW = new long[N + 1];
      foreach (i; 0 .. N) {
        sumV[i + 1] = sumV[i] + P[i].v;
        sumW[i + 1] = sumW[i] + P[i].w;
      }
      
      const ans = dfs(0, W);
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}