#include <fstream>

using namespace std;
int p[1001][5001];
int main()
{ FILE *f,*g;
f=fopen("energii.in","r");
g=fopen("energii.out","w");
int w,i,G,e[10001],c[10001],j,s=0,s1=0,k,min;
fscanf(f,"%d %d",&G,&w);
for(i=1;i<=G;i++)
fscanf(f,"%d %d",&e[i],&c[i]);
for(i=1;i<=G;i++)
  for (j=1;j<=w;j++)
 if (e[i]<j)
    { s=0;s1=0;
        for(k=1;k<=i;k++)
        s=s+e[k];
    if (s<j)
         p[i][j]=-e[i];
       else
         {for(k=1;k<=i;k++)
           s1=s1+c[k];
           p[i][j]=s1;
         }
    }
   else
     p[i][j]=c[i];
     min=2000000;
 for(i=1;i<=G;i++)
  if (min>p[i][w]&&p[i][w]>0) {min=p[i][w];}
fprintf(g,"%d",min);
/*for(i=1;i<=G;i++)
{for(j=1;j<=w;j++)
fprintf(g,"%d ",p[i][j]);
fprintf(g,"\n");}*/
    return 0;
}