/*
TASK:lift
LANG:C++
*/
#include<iostream>
#include<vector>
using namespace std;
struct pass
{ int h;int w;};
int main()
 { int n;int t;
   cin>>n>>t;
   int i;
   vector<pass> a;
   for(i=0;i<n;i++)
    { pass g;
      cin>>g.h>>g.w;
       a.push_back(g);
    }
   int l=0;
   for(i=0;i<a.size();i++)
    if(a[i].w>t){l=1;break;}
    if(l==1)cout<<"0\n";
    else
    { int s=0;int i;
      for(i=0;i<a.size();i++)
      s+=a[i].h;
      cout<<s<<"\n";
    }
}       
                     
