#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <cmath>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <iostream>
#include <random>
#include <map>
#include <iomanip>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <cassert>
#include <fstream>
#include <unordered_map>
#include <cstdlib>
#include <complex>
#include <cctype>
#include <bitset>
using namespace std;

using ll = long long;
using vll = vector<long long>;
using pll = pair<long long, long long>;
#define REP(i,n) for(long long i(0);(i)<(n);(i)++)


void solve(long long N){
    cout << (N-2)*180 << endl;
}

int main(){
    long long N;
    scanf("%lld",&N);
    solve(N);
    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;
}
