#include<fstream.h>
long a[2][10002],i,j,g,w,c,e;
int main()
{
for (i=1;i<=10000;i++)
{
	a[0][i]=100000000;
}
ifstream f("energii.in");
f>>g>>w;
for (i=1;i<=g;i++)
{
	f>>e>>c;
	for (j=1;j<e;j++)
		a[1][j]=a[0][j];
	for (j=e;j<=10000;j++)
	{
		a[1][j]=a[0][j];
		if (a[0][j-e]+c<a[1][j])a[1][j]=a[0][j-e]+c;
	}
	for (j=1;j<=10000;j++)a[0][j]=a[1][j];
}
f.close();
long max=100000000;
for (i=w;i<=10000;i++)
	if (a[0][i]<max)max=a[0][i];

ofstream out("energii.out");
	out<<max;
out.close();


return 0;
}