#include <bits/stdc++.h> using namespace std; int n; int main() { cin>>n; if(n<=30) printf("%.2lf",n0.2); else if(n>30 && n<=60) printf("%.2lf",300.2+(n-30)*0.6); else cout<<"NO"; return 0; }

using namespace std;
int main()
{
  double a,b,c;
  cin>>a;
  if(a<=30){
  	cout << fixed << setprecision(2) << a*0.2 << endl;
  }else if(a>30 and a<=60){
  	cout << fixed << setprecision(2) << (a-30)*0.6+6 << endl;
  }else if(a>60){
  	cout<<"NO"<<endl;
  }
  return 0;
}

洒家打破了五五开的局面╰(°▽°)╯

上过初中的都会做吧

using namespace std;
int main()
{
  double a,b,c;
  cin>>a;
  if(a<=30){
  	cout << fixed << setprecision(2) << a*0.2 << endl;
  }else if(a>30 and a<=60){
  	cout << fixed << setprecision(2) << (a-30)*0.6+6 << endl;
  }else if(a>60){
  	cout<<"NO"<<endl;
  }
  return 0;
}