#pragma GCC optimize ("O2")
#pragma GCC target ("avx2")
//#include<bits/stdc++.h>
//#include<atcoder/all>
//using namespace atcoder;
#include<iostream>
#include<cstring>

using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please

const int IM = 2e9;
int dat[400004];

const int CM = 1 << 17, CL = 12;
char cn[CM + CL], * ci = cn + CM + CL, * owa = cn + CM, ct;
const ll ma0 = 1157442765409226768;
const ll ma1 = 1085102592571150095;
const ll ma2 = 71777214294589695;
const ll ma3 = 281470681808895;
const ll ma4 = 4294967295;
inline int getint() {
	if (ci - owa > 0) {
		memcpy(cn, owa, CL);
		ci -= CM;
		fread(cn + CL, 1, CM, stdin);
	}
	ll tmp = *(ll*)ci;
	if ((tmp & ma0) ^ ma0) {
		int dig = 68 - __builtin_ctzll((tmp & ma0) ^ ma0);
		tmp = tmp << dig & ma1;
		tmp = tmp * 10 + (tmp >> 8) & ma2;
		tmp = tmp * 100 + (tmp >> 16) & ma3;
		tmp = tmp * 10000 + (tmp >> 32) & ma4;
		ci += (72 - dig >> 3);
	}
	else {
		tmp = tmp & ma1;
		tmp = tmp * 10 + (tmp >> 8) & ma2;
		tmp = tmp * 100 + (tmp >> 16) & ma3;
		tmp = tmp * 10000 + (tmp >> 32) & ma4;
		ci += 8;
		if ((ct = *ci++) >= '0') {
			tmp = tmp * 10 + ct - '0';
			if (*ci++ == '0') {
				tmp = tmp * 10;
				ci++;
			}
		}
	}
	return tmp;
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	int N = getint();
	dat[0] = -IM;
	ll kotae = -IM * ll(N);
	for (int i = N + 1; i > 1; i--) {
		dat[i] = getint();
		kotae += dat[i];
	}

	for (int i = 2; i < N + 2; i++) {

		int p = 2 + (dat[2] > dat[3]);
		int v = dat[i] - IM;
		while (v > dat[p]) {
			dat[p >> 1] = dat[p];
			p <<= 1;
			p += dat[p] > dat[p + 1];
		}
		dat[p >> 1] = v;

		int a = getint();
		kotae += a;
		p = i;
		v = a - IM;
		while (v < dat[p >> 1]) dat[p] = dat[p >> 1], p >>= 1;
		dat[p] = v;

		kotae -= dat[1];
	}

	co(kotae);

	Would you please return 0;
}
#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
using ll =long long;
using vi = vector<ll>;
using vc = vector<char>;
using vs = vector<string>;
using P = pair<ll , ll>;
using vp = vector<P>;
#define rep(i, n) for (long long int i = 0; i < n; i++)
#define rep2(i, s, n) for (int i = (s); i < n; i++)
#define sort(A) sort(A.begin(),A.end());
#define reverse(A) reverse(A.begin(),A.end());
#define vecint2(A, n, m) vector<vector<long long int>> A(n, vector<long long int>(m));
#define vecchar2(A, n, m) vector<vector<char>> A(n, vector<char>(m));
#define k(s) cout << fixed << setprecision(s);
#define t cout<<"OK"<<endl;
#define Yes cout<<"Yes"<<endl
#define No cout<<"No"<<endl
#define YES cout<<"YES"<<endl
#define NO cout<<"NO"<<endl
const long double pi=3.14159265358979323846;

int main() {
  int N;
  cin>>N;
  vector<string> S(N);
  rep(i,N) cin>>S[i];
  ll dpf[65],dpt[65];
  dpf[0]=1;dpt[0]=1;
  rep(i,N){
    if(S[i]=="AND"){
      dpt[i+1]=dpt[i];
      dpf[i+1]=2*dpf[i]+dpt[i];
    }else{
      dpt[i+1]=2*dpt[i]+dpf[i];
      dpf[i+1]=dpf[i];
    }
  }
  cout<<dpt[N]<<endl;
}