C :

#include<stdio.h>
void main() 
{
	int n;
	double m;
	scanf("%d",&n);
    n=n*1.0;
	m=(n-2.0)*180/n;
	printf("%.1f",m);
}

C++ :

#include<bits/stdc++.h>
using namespace std;
int main(){

	double n;
	cin>>n;
	cout<<fixed<<setprecision(1)<<((n-2)*180)/n<<endl;


	return 0;
}

Pascal :

var
  n,a,b:longint;
  s:real;
begin
  read(n);
  a:=(n-2)*180;
  s:=a/n;
  write(s:0:1);
end.

Java :

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		//定义正多边形内角和为s
		int s = (n-2)*180;
		//该正n边形每个内角的度数
		double i ;
		i = s / (n * 1.0);
		System.out.printf("%.1f",i);
	}
}

Python :

#!/usr/bin/env python3
  
n = int(input())
s = (n-2)*180
f = s/n
print("%.1f"% f)