#include<bits/stdc++.h>
using namespace std;
struct coin{
    int m,v,p;
};
bool cmp(coin x,coin y){
    return x.v*y.m>y.v*x.m;
}
int main(){
    int n,t;
    double sum;
    cin>>n>>t; 
    coin a[101];
    for(int i=1;i<=n;i++){
        cin>>a[i].v>>a[i].m;
        a[i].p=a[i].v/a[i].m;
    }
    sort(a+1,a+n+1,cmp);
    for(int i=1;i<=n;i++){
        if(t>=a[i].m){
            t-=a[i].m;
            sum+=a[i].v;
        }
        else{
            sum+=t*a[i].p;
            break;
        }
    }
    printf("%2d",sum);
    return 0;
}