#include<iostream>
#include<fstream>
using namespace std;
int main()
{int g,w,eg[10000],cg[10000],r[10000],i,j,s=0,aux;
ifstream f("energii.in");
f>>g>>w;
for(i=1;i<=g;i++)
	{f>>eg[i]>>cg[i];
	r[i]=eg[i]/cg[i];
	}
f.close();
for(i=1;i<=g-1;i++)
	for(j=i+1;j<=g;j++)
		if(r[i]<r[j]){aux=r[i]; r[i]=r[j];r[j]=aux;}
while(s<w)
	{s+=cg[i]; i++;}
cout<<s;
}