/* Energii */
#include<fstream>
using namespace std;

ifstream f("energii.in");
ofstream g("energii.out");

int n,w,i,j;
int m[100][100];
int e[100],c[100];

int main()
{f>>n>>w;
for(i=1; i<=n; i++)
  f>>e[i]>>c[i];
for(i=1; i<=n; i++)
 for(j=1; j<=w; j++)
   {if(j>e[i])
     {if((m[i-1][j]==0 || m[i-1][j]>m[i-1][j-e[i]]+c[i]) && m[i-1][j-e[i]]!=0)
        m[i][j]=m[i-1][j-e[i]]+c[i];
     else
        m[i][j]=m[i-1][j];} 
    else       
     {if(m[i-1][j]==0 || c[i]<m[i-1][j])
         m[i][j]=c[i];
      else
         m[i][j]=m[i-1][j];}  
    }

 g<<endl;}      
g<<m[n][w];               
return 0;}