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

string FMT_F = "%.10f";

T RD(T = long)() { static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res.to!T; }
string RDR()() { return readln.chomp; }
T[] ARR(T = long)(in string str, T fix = 0) { auto r = str.split.to!(T[]); r[] += fix; return r; }
size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;}
size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; }

bool inside(T)(T x, T b, T e) { return x >= b && x < e; }
bool minimize(T)(ref T x, T y) { if (x > y) { x = y; return true; } else { return false; } }
bool maximize(T)(ref T x, T y) { if (x < y) { x = y; return true; } else { return false; } }

long mod = 10^^9 + 7;
void moda(ref long x, long y) { x = (x + y) % mod; }
void mods(ref long x, long y) { x = ((x + mod) - (y % mod)) % mod; }
void modm(ref long x, long y) { x = (x * y) % mod; }

void main()
{
	auto N = RD;
	auto W = RD;
	long[2][][4] wv;
	wv[0] ~= [RD, RD];
	long base_w = wv[0][0][0];
	foreach (i; 1..N)
	{
		auto w = RD;
		auto v = RD;
		wv[w-base_w] ~= [w, v];
	}
	foreach (ref e; wv)
		e.sort!"a[1] > b[1]"();

	long[2][][4] dp;
	foreach (i; 0..4)
	{
		dp[i] ~= [0, 0];
		foreach (j; 0..wv[i].length)
		{
			dp[i] ~= [dp[i][j][0] + wv[i][j][0], dp[i][j][1] + wv[i][j][1]];
		}
	}

	stderr.writeln(wv);
	stderr.writeln(dp);

	long ans;
	foreach (i; 0..dp[0].length)
	{
		foreach (j; 0..dp[1].length)
		{
			foreach (k; 0..dp[2].length)
			{
				foreach (l; 0..dp[3].length)
				{
					if (dp[0][i][0] + dp[1][j][0] + dp[2][k][0] + dp[3][l][0] > W) continue;
					ans = max(ans, dp[0][i][1] + dp[1][j][1] + dp[2][k][1] + dp[3][l][1]);
				}
			}
		}
	}

	writeln(ans);
	stdout.flush();
}