#include<bits/stdc++.h>
using namespace std;
int main()
{ int a;
 cin >>a;
 float n;
  if(a<=150) {
    n=a*0.4463;
  } else  if(a<=400) n=150*0.4463+(a-150)*0.4663;
  	        else n=150*0.4463+250*0.4663+(a-400)*0.5663;
  	        printf("%.1f",n);
  	
  	
  	
  
    

	return 0;
}


/**************************************************************
	Problem: 1463
	User: cx001
	Language: C++
	Result: Accepted
	Time:20 ms
	Memory:2072 kb
****************************************************************/