die码
#include<bits/stdc++.h>
using namespace std;
int N,T,cnt,i;
float ans;
struct corn{
int m,v,z;
}a[1001];
bool cmp(corn x,corn y){
return x.z<y.z;
}
int main(){
cin>>N>>T;
for(i=1;i<=N;i++){
cin>>a[i].m>>a[i].v;
a[i].z=a[i].v/a[i].m;
}
sort(a+1,a+N+1,cmp);
for(i=N;i>0;i--){
cnt+=a[i].m;
ans+=a[i].v;
if(cnt>T){
ans=ans-(cnt-T)*a[i].z;
break;
}
}
printf("%.2lf",ans);
return 0;
}