C :

#include <stdio.h>

void main()
{
float c,f;
scanf("%f",&f);
c=5.0/9*(f-32);
printf("%.4f",c);
}

C++ :

#include<iostream>
using namespace std;

int main()
{
	double f,c;
	cin>>f;
        c=5.0/9*(f-32);
	cout<<c<<endl;
	return 0;
}