#include <bits/stdc++.h>
using namespace std;
#define int long long
struct oper;
struct oper {
int id, type, subsize;
oper* left = nullptr;
oper* right = nullptr;
oper(int d, int t) {
id = d;
type = t;
subsize = t == 0;
}
oper* assign(oper* lol) {
if (left == nullptr) {
left = lol;
return left;
} else {
right = lol;
return right;
}
}
};
int split;
void dfs(oper* curr) {
// cout<<(curr->id)<<'\n';
// cout.flush();
if (curr->type == 0) return;
dfs(curr->left);
dfs(curr->right);
if (curr->type == split) {
curr->subsize = curr->left->subsize + curr->right->subsize;
} else {
curr->subsize = min(curr->left->subsize, curr->right->subsize);
}
}
void reset(oper* curr) {
// cout<<(curr->id)<<'\n';
// cout.flush();
if (curr->type == 0) {
curr->subsize = 1;
} else {
curr->subsize = 0;
if (curr->right == nullptr) {
cout<<"WTF\n";
} else {
// cout<<'i'<<(curr->left->id)<<endl;
// cout.flush();
// cout<<'i'<<(curr->right->id)<<endl;
// cout.flush();
reset(curr->left);
reset(curr->right);
}
}
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
int N = 0;
string arson;
cin>>arson;
oper* root = nullptr;
oper* curr = nullptr;
oper* junk = nullptr;
stack<oper> ord;
for (int i = 0; i < arson.size(); ++i) {
// cout<<arson[i];
// cout.flush();
if (arson[i] == 'x') { //max
if (root == nullptr) {
root = new oper(i, 1);
curr = root;
} else {
// cout<<(curr->id)<<endl;
curr = curr->assign(new oper(i, 1));
}
ord.push(*curr);
} else if (arson[i] == 'n') { //min
if (root == nullptr) {
root = new oper(i, 2);
curr = root;
} else {
// cout<<(curr->id)<<endl;
curr = curr->assign(new oper(i, 2));
}
ord.push(*curr);
} else if (arson[i] == '?') {
++N;
if (root == nullptr) break;
// cout<<(curr->id)<<endl;
curr->assign(new oper(i, 0));
} else continue;
while (!ord.empty() && curr->left != nullptr && curr->right != nullptr) {
*curr = ord.top();
ord.pop();
}
}
if (N == 1) {
cout<<"1";
} else {
// cout<<"MARK 1\n";
reset(root);
split = 1;
// cout<<"MARK 2\n";
dfs(root);
int maxval = root->subsize;
// cout<<maxval<<' ';
// cout<<"MARK 3\n";
reset(root);
split = 2;
// cout<<"MARK 4\n";
dfs(root);
// cout<<"MARK 5\n";
int minval = root->subsize;
maxval = N - maxval;
cout<<(abs(maxval - minval));
}
}
