#include<iostream>
#include<iomanip>
using 
 namespace std;

int main()
{
	int i;
	float a,b,c;
	a=0.4463;
	b=0.5633;
	cout<<"请输入月用电量"<<endl;
	cin>>i; 
	if(i<=150)
	{
		c=i*a;
		cout<<fixed<<setprecision(1);
		cout<<"电费为"<<c;
	}
	else if(i>150&&i<=400)
	{
		c=150*0.4463+(i-150)*0.4663;
		cout<<fixed<<setprecision(1);
		cout<<"电费为"<<c;
	}
	else
	{
		c=150*0.4463+250*0.4663+(i-400)*0.5663;
		cout<<fixed<<setprecision(1);
		cout<<"电费为"<<c;
	}
	
}