Farhenheit to celsius conversion ; Test case 1 failed

#1 
  #include<iostream>        
 using namespace std;
 int main() {
int max;
int min;
int step;
cin>>min;
cin>>max;
cin>>step;
int c=0;
int f=min;
while (f<=max) {
	c=((5*(f-32))/9);
	cout<<f<<" "<<c<<endl;
	f=f+20;
}
return 0;

}

#2

@Maazkhan you are updating f as f+20 but it should be f=f+step.