/*
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
*/
// lethal option
#include<bits/stdc++.h>
using namespace std;
#define all(flg) flg.begin(), flg.end()
#define int long long
#define pb push_back
#define fi first
#define se second
#define endl "\n"
#define eb emplace_back
#define ii pair<int, int>
#define vi vector<int>
#define PI 3.141592653589793238462643383279502884
#define ll long long
#define ld long double
#define for1(i, ff, gg) for(int i = ff; i <= gg; ++i)
#define for2(i, ff, gg) for(int i = ff; i >= gg; --i)
const ll mod = 1e9 + 7;
const int maxN = 2e6 + 5;
const ll oo = 1e18 + 7;
int n = 0, a[maxN];
int x, y, z, k;
vi vc[maxN];
bool tag[maxN];
int dfs_build(){
int node = ++z;
char c; cin >> c; if(c == '?'){
++n; return node;
}
cin >> c >> c;
tag[node] = (c == 'n');
cin >> c; vc[node].pb(dfs_build());
cin >> c; vc[node].pb(dfs_build());
cin >> c;
return node;
}
int dfs_calc(int node){
if(vc[node].empty()) return 1;
int v1 = dfs_calc(vc[node][0]);
int v2 = dfs_calc(vc[node][1]);
if(tag[node]) return v1 + v2;
else return min(v1, v2);
}
signed main(){
// freopen(".inp", "r", stdin);
ios_base::sync_with_stdio(0);
cin.tie(NULL);
cout.tie(NULL);
z = 0; dfs_build();
int ans = n + 2;
ans -= dfs_calc(1);
for1(i, 1, z) tag[i] = !tag[i];
ans -= dfs_calc(1);
cout << ans << endl;
}
