#include<bits/stdc++.h>
#define ll long long int
#define mk make_pair
#define pb push_back
#define INF (ll)1e18
#define pii pair<ll,ll>
#define mod 1000000007 //998244353
#define f(i,a,b) for(ll i=a;i<b;i++)
#define fb(i,a,b) for(ll i=a;i>b;i--)
#define ff first
#define ss second
#define srt(v)  if(!v.empty())sort(v.begin(),v.end())
#define rev(v)  if(!v.empty())reverse(v.begin(),v.end())
#define PI 3.141592653589793238
#define pqr priority_queue<ll,vector<ll>,greater<ll>()>
using namespace std;
ll pow_mod(ll a,ll b)
{
	ll res=1;
	while(b!=0)
	{
		if(b&1)
		{
			res=(res*a)%mod;
		}
		a=(a*a)%mod;
		b/=2;
	}
	return res;
}
void solve()
{
  ll n;
  cin>>n;
  
  string s[n];
  
  for(ll i=0;i<n;i++)
  cin>>s[i];
  
  ll ans=0;
  
  for(ll i=n-1;i>=0;i--){
      if(s[i]=="OR")
      {
          ans+=(ll)pow(2,i+1);
      }
      
      if(i==0){
        ++ans;
      }
     
  }
  cout<<ans<<endl;
}
int main()
{    ios_base::sync_with_stdio(false);
     cin.tie(NULL);
     cout.tie(NULL);
     
//Start from Here.

  ll t;
  t=1;
 //cin>>t;
  while(t--)
  solve();
  
//Good Bye!
    return 0;
}

// Problem : A - ReLU
// Contest : AtCoder - AtCoder Beginner Contest 183
// URL : https://atcoder.jp/contests/abc183/tasks/abc183_a
// Memory Limit : 1024 MB
// Time Limit : 2000 ms
// Powered by CP Editor (https://github.com/cpeditor/cpeditor)

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

#define int long long
#define db double
#define mod 1000000007
#define pb push_back
#define pp pair<int,int>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define repe(i,a,b) for(int i=a;i<=b;i++)
#define repr(i,a,b) for(int i=b;i>=a;i--)
#define maxn 200005
#define ss second
#define ff first
#define all(a) a.begin(),a.end()
#define lb lower_bound
#define ub upper_bound
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> 
int inv(int a, int b){
 return 1<a ? b - inv(b%a,a)*b/a : 1;
}
int test =1;
void solve()
{
	//cout << "Case #"<< test++<<": ";
	int x;
	cin >> x;
	cout << max(x,(int)0);
}
signed main()
{
	ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t=1;
    //cin >> t;
    while(t--)
    solve();
    return 0;
}
