#include <stdio.h>;
FILE *f =fopen("energii.in","r");
FILE *g=fopen("energii.out","w");
struct date
{
int eng ;
int cost;
} a[10000];
int G,W;
int cmin;
int main(void)
{
int i,j,ct,en,een,ccs;
int cost[10000]   ;
cmin=10000;
fscanf(f,"%d\n",&G);
fscanf(f,"%d\n",&W);
for  (i=1;i<=G;i++)
{
fscanf(f,"%d %d \n ",&a[i].eng,&a[i].cost);
cost[i]=a[i].cost;
if (a[i].eng>=W)
if (cmin>a[i].cost)
cmin=a[i].cost;
}
for (i=1;i<=G-1;i++)
{
ct=10000;
for (j=i;j<=G;j++)
if (ct>a[i].cost+a[j].cost)
{
en=a[i].eng+a[j].eng;
ct=a[i].cost+a[j].cost;
}
if (een<W)
{
een+=en;
ccs+=ct;
}
else
break;
}
if (ccs<cmin)
fprintf(g,"%d",ccs)   ;
else
fprintf(g,"%d",cmin );
fclose(g);
return(0);
}