#include<bits/stdc++.h>
#define int long long
using namespace std;
inline int read()//快读
{
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
vector<int> w;
vector<int> v;
signed main(){
int n=read(),t=read();
for(int i=1;i<=n;i++){
int wi,vi;
vi=read(),wi=read();
w.push_back(wi);
v.push_back(vi);
}
for(int i=0;i<w.size();i++){
for(int j=i+1;j<w.size();j++){
double q1=double(double(w[i])/double(v[i]));
double q2=double(double(w[j])/double(v[j]));
if(q1<q2){
swap(w[i],w[j]);
swap(v[i],v[j]);
}
}
}
int i=0;
double ans=0.0;
while(t>0 && i<n){
if(t>=v[i]){
ans+=double(w[i]);
t-=v[i];
i++;
}else{
double s;
s=double(double(w[i])/double(v[i]));
ans=ans+double(t)*s;
t=0;
i++;
}
}
printf("%.2lf",ans);
return 0;
}
怎么错了啊qwq