#include<iostream.h>
#include<fstream.h> 
float p,c,h, n,min=5002,aux,aux1,v[1000],v1[1000],gasit,s,ok;
int main()
{ifstream f("energii.in");
ofstream g("energii.out");
f>>n>>h;

for(int i=1;i<=n;i++)
{f>>v[i]>>v1[i];
}
while(gasit)
{gasit=0;
for(i=1;i<n;i++)
if(v1[i]>v1[i+1])
{aux=v1[i];aux1=v[i];
v1[i]=v1[i+1];v[i]=v[i+1];
v1[i+1]=aux;v[i+1]=aux1;
gasit=1;}
}    i=1;s=0;
while(ok)
{s=s+v[i];
if(s>=h)
ok=0;
i++;}

g<<s;
f.close();
g.close();
return 0;
}