#include <stdio.h>
#include <algorithm>
#include <vector>
#define MAXN 4000000

using namespace std;

struct generator
{
	int c;
	int e;
};

int best[MAXN];
bool viz[MAXN];
vector<generator> gn;

bool cmpf(const generator v1,const generator v2)
{
	return v1.e > v2.e;
}

int main()
{
	freopen("energii.in","r",stdin);
	freopen("energii.out","w",stdout);

	int nrg,cmin,i,j,min = 99999999;
	generator aux;
	aux.e = 9999999;
	aux.c = 1;
	gn.push_back(aux);
	scanf("%d",&nrg);
	scanf("%d",&cmin);
	for (i=1;i<=nrg;i++)
	{
		scanf("%d%d",&aux.e,&aux.c);
		gn.push_back(aux);
	}
	sort(gn.begin(),gn.end(),cmpf);
	best[0] = 0;
	for (i=1;i<=nrg;i++)
	{
		if (best[gn[i].c]<gn[i].e)
		{
			best[gn[i].c] = gn[i].e;
			viz[gn[i].c] = true;
			if (best[gn[i].c]>=cmin)
			{
				if (gn[i].c<min)
				{
					min = gn[i].c;
				}
			}
		}
		for (j=1;j<=cmin;j++)
		{
			if (viz[j])
			{
				viz[j] = false;
			}
			else if (best[j] != 0)
			{
				if (best[j+gn[i].c] < best[j]+gn[i].e)
				{
					best[j+gn[i].c] = best[j] + gn[i].e;
					viz[j+gn[i].c] = true;
				}
				if (best[j] + gn[i].e>=cmin)
				{
					if (j+gn[i].c<min)
					{
						min = j+gn[i].c;
					}
					break;
				}
			}
		}
	}
	if (min != 99999999)
	{
		printf("%d",min);
	}
	else
	{
		printf("-1");
	}
	return 0;
}