#include<stdio.h>

int e[1002],c[1002],v[2004],a[2004],i,k,j,g,w,min;

int main () {
    FILE *f = fopen("energii.in","r");
    FILE *t = fopen("energii.out","w");
    
    fscanf(f,"%d %d",&g,&w);
    for(i=1;i<=g;i++)
                     fscanf(f,"%d %d",&e[i],&c[i]);
    k=0;
    for(i=1;i<=g;i++){
            v[++k]=e[i];
            a[k]=c[i];
            for(j=i+1;j<=g;j++){
                       v[++k]=e[i]+e[j];
                       a[k]=c[i]+c[j];                 
                       }
                       }
     min=10001;
     for(i=1;i<=k;i++)
                      if(v[i]>=w&&a[i]<min)
                                           min=a[i];
    if(min==10001)
		  fprintf(t,"%d",-1);
	 else
		  fprintf(t,"%d",min);
    
    
    
    fclose(f);
    fclose(t);
return 0;
}