#include <bits/stdc++.h>
#define sz(arr) (int)arr.size()
#define all(arr) arr.begin(), arr.end()

using namespace std;

void _cin() {}
template <class Head, class... Tail>
void _cin(Head&& head, Tail&&... tail) {
  cin >> head;
  _cin(forward<Tail>(tail)...);
}

#define Cin(T, ...) \
  T __VA_ARGS__;    \
  _cin(__VA_ARGS__)

int main() {
  Cin(int, n);
  cout << 180 * (n - 2) << endl;

  return 0;
}
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <math.h>
#include <map>

using namespace std;

int main(){
	double n;
	cin >> n;
	cout << n*(180-(360/n)) << endl;
	return 0;
}
