#include<bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define in insert
#define all(x) x.begin(),x.end()
#define pb push_back
#define eb emplace_back
#define ff first
#define ss second
// #define int long long
typedef long long ll;
typedef vector<int> vi;
typedef set<int> si;
typedef multiset<int> msi;
typedef pair<int, int> pii;
typedef vector<pii> vpii;
template<typename T, typename U>
ostream & operator << (ostream &out, const pair<T, U> &c) {
out << c.first << ' ' << c.second;
return out;
}
template<typename T>
ostream & operator << (ostream &out, vector<T> &v) {
const int sz = v.size();
for (int i = 0; i < sz; i++) {
if (i) out << ' ';
out << v[i];
}
return out;
}
template<typename T>
istream & operator >> (istream &in, vector<T> &v) {
for (T &x : v) in >> x;
return in;
}
template<typename T>
void mxx(T &a, T b){if(b > a) a = b;}
template<typename T>
void mnn(T &a, T b){if(b < a) a = b;}
const int mxn = 5e6 + 10;
char str[mxn];
pair<int, int> merge(pair<int, int> a, pair<int, int> b, int tp) {
pair<int, int> ret{0, 0};
if(tp == 1) {
ret.ff = a.ff + b.ff + 1;
ret.ss = min(a.ss, b.ss);
} else {
ret.ff = min(a.ff, b.ff);
ret.ss = a.ss + b.ss + 1;
}
return ret;
}
void go() {
cin >> str + 1;
int n = strlen(str + 1);
int tot = 0;
stack<tuple<pair<int, int>, pair<int, int>, int>> s;
pair<int, int> ans{0, 0};
function<void(pair<int, int>)> add = [&](pair<int, int> dp) {
if(s.size() == 0) {
ans = dp;
return;
}
pair<int, int> a1, a2;
int tp;
tie(a1, a2, tp) = s.top();
s.pop();
if(a1.ff == -1) {
s.push(make_tuple(dp, a2, tp));
} else {
add(merge(a1, dp, tp));
}
};
for(int i = 1; i <= n; i++) {
if(str[i] == 'm') {
s.push(make_tuple(make_pair(-1, -1), make_pair(-1, -1), (str[i + 1] == 'a')));
} else if(str[i] == '?') {
tot++;
add(make_pair(0, 0));
}
}
cout << tot - ans.ff - ans.ss << '\n';
}
signed main() {
// #ifndef ONO
// freopen("file.in", "r", stdin);
// freopen("file.out", "w", stdout);
// #endif
fast;
int t = 1;
// cin >> t;
while(t--) {
go();
}
return 0;
}
