#include <cstdio>
using namespace std;

FILE *f=fopen("energii.in","r");
FILE *g=fopen("energii.out","w");

int n,w;
int v[15001],minim=1<<30;

int main()
{int i,j,a,b;
fscanf(f,"%d %d",&n,&w);


for (i=1;i<=15000;i++) v[i]=1<<30;
while (n!=0)
        {fscanf(f,"%d %d",&a,&b);
         for (i=5000;i>=0;i--) if (v[i]+b<v[i+a]) v[i+a]=v[i]+b;
         n--;
         }
for (i=15000;i>=w;i--) if (v[i]<minim) minim=v[i];
fprintf(g,"%d\n",minim);
return 0;
}