#include<bits/stdc++.h>
using namespace std;
int main(){
	double a,b;
	cin>>a>>b;
    double n=a-b*0.8;
	printf("%.1lf",n);
	return 0;
}

C++ :

#include<bits/stdc++.h>
using namespace std;
int main(){
	double a,b;
	cin>>a>>b;
	cout<<fixed<<setprecision(1)<<a-b*0.8;
	return 0;
}

Python :

# coding=utf-8
n=int(input())
m=int(input())
a=n-m*8/10
print(round(a,1))