#include<stdio.h>
long x[5002],i,j,n,m,k,l,a,z,s[5002],y[5002];
int main()
{
	freopen("energii.in","r",stdin);
	freopen("energii.out","w",stdout);

	scanf("%ld%ld",&n,&m);
	for (i=1;i<=n;i++)
	scanf("%ld%ld",&x[i],&y[i]);
	s[0]=1;
	for (i=1;i<=n;i++)
		for (j=m;j>=0;j--)
			if (s[j]) if ((s[j+x[i]]&&s[j+x[i]]>s[j]+y[i])||(s[j+x[i]]==0)) {s[j+x[i]]=s[j]+y[i];}
	z=2000000000;
	for (i=m;i<=5001;i++)
	if (s[m]<z&&s[m]!=0) {z=s[m];}
	if (z==2000000000) z=0;
	printf("%ld\n",z-1);
	return 0;
}