1.4-13:分段函数

#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
	double x,y;
	cin>>x;
    if(x<5 && x>=0) y=-x+2.5;
	else if(x<10) y=2-1.5*(x-3)*(x-3);  
	else y=x/2-1.5;
	cout<<fixed<<setprecision(3)<<y;
	return 0;
}