#include<bits/stdc++.h>
#define ll long long 
#define pb push_back
#define ff first
#define ss second
#define setbits(x)          __builtin_popcountll(x)
#define lp(a,n) for(ll i=a; i<n; i++)
#define lpi(a,n) for(int i=a; i<n; i++)
#define w(t) int t; cin>>t; while(t--)
#define vi vector<int> 
#define vll vector<ll>
#define pll pair<ll, ll>
#define pii pair<int, int>
#define inf 1e9
#define LB lower_bound
#define UB upper_bound
const int mod = 1000000007;
using namespace std;
ll gcd(ll a,ll b){
    if(a==0)return b;
    return gcd(b%a,a);
}
ll lcm(ll a, ll b){
    return (a*b)/gcd(a,b);
}
 
int prime[100007];
void SieveOfEratosthenes(int n) 
{ 
    memset(prime, -1, sizeof(prime)); 
  
    for (int p=2; p*p<=n; p++) 
    { 
         
        if (prime[p] == -1) 
        { 
            for (int i=p*p; i<=n; i += p) 
                prime[i] = p; 
        } 
    } 
    
} 
int lps(string s){
    int len = 0;
    int n = s.length();
    int dp[n];
    dp[0] = 0;
    for(int i=1; i<n; i++){
        if(s[i] == s[len]){
            len++;
            dp[i] = len;
            continue;
        }
        if(len!=0){
            len = dp[len-1];
            i--;
            continue;
        }
        dp[i]=0;
    }
    return dp[n-1];
}
 
ll power(unsigned ll x,unsigned  ll y) 
{ 
    ll res = 1;     
    while (y > 0) 
    { 
        if (y & 1) 
            res = res*x; 
   
        y = y>>1;
        x = x*x;  
    } 
    return res; 
}
 
//to calculate p1^x  *  p2^x2  *p3^x3 ----------
//i.e. prime factorization and store pi and xi in vector 
vector<pair<ll, ll>> pFactor;
 
void factorize(long long n) 
{ 
    int count = 0; 
  
    // count the number of times 2 divides  
    while (!(n % 2)) { 
        n >>= 1; // equivalent to n=n/2; 
        count++; 
    } 
  
    // if 2 divides it 
    if (count) 
        pFactor.pb({2,count}); 
  
    // check for all the possible numbers that can  
    // divide it 
    for (long long i = 3; i <= sqrt(n); i += 2) { 
        count = 0; 
        while (n % i == 0) { 
            count++; 
            n = n / i; 
        } 
        if (count) 
            pFactor.pb({i,count});
    } 
  
    // if n at the end is a prime number. 
    if (n > 2) 
        pFactor.pb({n,1}); 
} 

 
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
    ll n;
    cin>>n;
    vector<string> v(n+1);
    int mx = -1;
    lp(1,n+1){
        cin>>v[i];
        if(v[i]=="OR"){
            mx = i;
        }
    }
    
    ll ans = 0;
    for(int i=n; i>=1; i--){
        if(v[i]=="AND"){
            continue;
        }
        ans += (1ll<<i);
    }
    ans++;
    cout<<ans<<endl;
}

#include <bits/stdc++.h>
using namespace std;
#define all(v) v.begin(),v.end()
#define MP make_pair
#define MT make_tuple
typedef int64_t ll;
#define PA pair<ll,ll>
#define TU tuple<ll,ll,ll>
#define vi vector<ll>
#define vii vector<vector<ll> >
#define rep(i,n) for(ll (i)=0; (i)<(ll)(n); (i)++)
#define rep2(i,m,n) for(ll (i)=(m); (i)<(ll)(n); (i)++)
const ll INF = 1ll<<30;
const ll INF2 = 1ll<<32;

int main() {
  ll n;
  cin >> n ;
  vector<bool> b(n,true);
  //ANDならfalse、ORならtrue
  rep(i,n) {
    string s;
    cin >>s;
    if(s=="AND") b.at(i) =false;
  }
  
  ll ans =0;
  for(ll i=n-1; i>=0; i--) {
    if(b.at(i)) ans += 1ll<<i+1;
  }
  cout << ans+1 << endl;
}