#include<stdio.h>
int i,j,v[6000],k,s,g,w,ok,min,y,x;
int main()
{
	freopen("energii.in","r",stdin);
	freopen("energii.out","w",stdout);
	scanf("%d%d",&g,&w);
	v[0]=1;
	for(j=1;j<=g;j++)
	{
		scanf("%d%d",&x,&y);
		for(i=20;i>=0;i--)
		{
			if(v[i]>0)
			{
				if(v[i+y]==0)
					v[i+y]=v[i]+x;
				else
				{
					if(x>v[i+y])
						v[i+y]=v[i]+x;
				}
				
			}
		}
	}
	min=9999999;
	for(i=1;i<=5000;i++)
	{
		if(v[i]>=w+1)
		{
			min=i;
			ok=1;
			break;
		}
	}
	if(ok==0)
		printf("%d",-1);
	else
		printf("%d",min);
	return 0;
}