#include <iostream> using namespace std; int main() { float x,y; cin>>x; if((x>=0)&&(x<5)) { y=2.5-x; } else if((x>=5)&&(x<10)) { y=2-1.5*(x-3)*(x-3); } else { y=x/2-1.5; } printf("%.3f",y); return 0; }