#include <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
using namespace std;
using ll = long long;
int main() {
    int n;
    cin >> n;
    vector <string> s(n);
    rep(i, n){
        cin >> s[i];
    }
    ll a = 1, b = 0;
    reverse(s.begin(), s.end());
    rep(i, n){
        if(s[i] == "AND"){
            a += b;
            b *= 2;
        }
        else{
            b += a;
            a *= 2;
        }
    }
    if(s[n - 1] == "AND"){
        cout << a + b << endl;
    }
    else{
        cout << a + b << endl;
    }
}


/*
Author : Chandan Agrawal
College : Poornima College of Engg. jaipur, Raj
Mail : chandanagrawal23@gmail.com
" when you are not practicing someone else is ,
 and the day u meet them u will lose "
*/
#include<bits/stdc++.h>
#include<stdio.h>
using namespace std;

#define fastio ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define MAX 100050

#define ll long long
#define ld long double
#define lli long long int

#define pb push_back
#define INF 1000000000000
#define mod 1000000007

// trignometric function always give value in Radians only
#define PI acos(-1) //3.1415926535897932384626433832795028
#define dsin(degree) sin(degree*(PI/180.0))
#define dcos(degree) cos(degree*(PI/180.0))
#define dtan(degree) tan(degree*(PI/180.0))

#define rsin(radian) sin(radian)
#define rcos(radian) cos(radian)
#define rtan(radian) tan(radian)

#define mem0(a) memset(a,0,sizeof(a))
#define mem1(a) memset(a,-1,sizeof(a))
#define memf(a) memset(a,false,sizeof(a))

#define loop(i,n)  for (lli i = 0; i < n; i++)
#define FOR(i,a,b) for (lli i = a; i < b; i++)

#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define makeuniq(v) v.resize(unique(all(v)) - v.begin()); //only uniq element in vector after this
#define sz(x) int(x.size())
#define F first
#define S second

#define mii map<lli,lli>

#define pii pair<lli,lli>

#define vi vector<lli>
#define vvi vector<vi>
#define vpi vector<pii>
#define vbool vector<bool>

#define seti set<lli>

#define gcd(a,b) __gcd((a),(b))
#define lcm(a,b) (a/gcd(a,b))*b
#define abs(x) ((x < 0)?-(x):x)

#define endl '\n'

template <typename Head>
void print(Head&& head)
{
    cout<<head<<endl;
}
template <typename Head, typename... Tail>
void print(Head&& head, Tail... tail)
{
    cout<<head<<" ";
    print(tail...);
}

#define scanarr(a,n) for(lli i=0;i<n;i++)    cin>>a[i];
#define scanvec(a,n) for(lli i=0;i<n;i++){ lli x ; cin>>x; a.pb(x);}

#define printarr(a,n) for(lli i=0;i<n;i++)   cout<<a[i]<<" "; cout<<endl;
#define printvec(vec) for(auto xt : vec) cout<<xt<<" ";    cout<<"\n";

#define FD(N) fixed<<setprecision(N)

#define deb(x) cout<<#x<<" "<<x<<endl;

/*
1D vector -  vi dp(n,value);
2D vector -  vvi dp(n,vi(n,value));
*/

// chandan1,2
void chandan1(){int y=1;return;}
void chandan2(){
        loop(i,10){
        lli x=1;
    }
    return(chandan1());
}


int main(){
fastio
lli t=1;
//cin>>t;
chandan2();
while(t--) {
    lli n;
    cin>>n;
    print(max(0LL,n));
  }
return 0;
}