#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define pi 3.141592653589793238
#define fast ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define MOD 1000000007

void solve()
{
	double r,g;
	cin>>r>>g;
	cout<<(g*2)-r;
    return;
}

int main()
{
        fast;
        ll q;
        q=1;
        // cin>>q;
        while(q--)
        	solve();
        
        return 0;
}
#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> P;
typedef long long ll; 

#define int ll

const ll mod = 1e9 + 7;


main(){
	int n;
	cin >> n;

	cout << (n-2)*180 << endl;

	return 0;
}
