#include<bits/stdc++.h>
using namespace std;
int main() {
	float q,z;
	cin>>q;
	if(q>=500){
		z=q*0.8;
	}else if(q>=300){
		z=q*0.9;
	}else{
		z=q;
	}
	printf("%.2f",z);
    return 0;
}

/**************************************************************
	Problem: 1871
	User: huangcanwu
	Language: C++
	Result: Accepted
	Time:30 ms
	Memory:2072 kb
****************************************************************/