//Language:Java
import java.util.*;

public class Dequy_Caitui {
	static int dequy(int[] value ,int mass[] ,int size)
	{
		if(size <= 0 ) return 0;
		int leng = value.length ,max = 0;
		for(int i = 0 ; i <leng ;i++)
		{
			if(size >= mass[i])
			{
				int tmp = value[i]+dequy(value,mass,size-mass[i]);
				max = max < tmp ? tmp:max;
			}
		}
		return max;
	}
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int num_item = sc.nextInt();
		int size = sc.nextInt();
		int value[] = new int[num_item];
		int mass[] = new int[num_item];

		for(int i = 0 ; i < num_item ;i++)
		{
			mass[i] = sc.nextInt();
			value[i] = sc.nextInt();
		}
		System.out.println(dequy(value,mass,size));
	}

}