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;
}