#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define REP(i,n) for(int i=0,_n=(int)(n);i<_n;++i)
#define ALL(v) (v).begin(),(v).end()
#define CLR(t,v) memset(t,(v),sizeof(t))
template<class T1,class T2>ostream& operator<<(ostream& os,const pair<T1,T2>&a){return os<<"("<<a.first<<","<<a.second<< ")";}
template<class T>void pv(T a,T b){for(T i=a;i!=b;++i)cout<<(*i)<<" ";cout<<endl;}
template<class T>void chmin(T&a,const T&b){if(a>b)a=b;}
template<class T>void chmax(T&a,const T&b){if(a<b)a=b;}


int nextInt() { int x; scanf("%d", &x); return x;}
ll nextLong() { ll x; scanf("%lld", &x); return x;}

int main2() {
  string s; cin >> s;
  int N = s.size();

  map<vector<int>, int> dp;
  dp.insert( make_pair( vector<int>(4), 0) ); // [0,0,0,0]
  REP(i, N) {
    if (string("KUROI?").find(s[i]) == string::npos) continue;
    map<vector<int>, int> ndp;
    for (auto it = dp.begin(); it != dp.end(); ++it) {
      const vector<int> state = it->first;
      const int val = it->second;
      vector<int> n_state = state;
      chmax(ndp[n_state], val);
      if (s[i] == 'K') {
        if (n_state[0] <= 20) n_state[0]++;
        chmax(ndp[n_state], val);
      }
      if (s[i] == 'U') {
        if (n_state[0] > 0) {
          n_state[0]--;
          if (n_state[1] <= 20) n_state[1]++;
          chmax(ndp[n_state], val);
        }
      }
      if (s[i] == 'R') {
        if (n_state[1] > 0) {
          n_state[1]--;
          if (n_state[2] <= 20) n_state[2]++;
          chmax(ndp[n_state], val);
        }
      }
      if (s[i] == 'O') {
        if (n_state[2] > 0) {
          n_state[2]--;
          if (n_state[3] <= 20) n_state[3]++;
          chmax(ndp[n_state], val);
        }
      }
      if (s[i] == 'I') {
        if (n_state[3] > 0) {
          n_state[3]--;
          chmax(ndp[n_state], val + 1);
        }
      }
      if (s[i] == '?') {
        for (char ch : string("KUROI")) {

            vector<int> n_state = state;
            if (ch == 'K') {
              if (n_state[0] <= 20) n_state[0]++;
              chmax(ndp[n_state], val);
            }
            if (ch == 'U') {
              if (n_state[0] > 0) {
                n_state[0]--;
                if (n_state[1] <= 20) n_state[1]++;
                chmax(ndp[n_state], val);
              }
            }
            if (ch == 'R') {
              if (n_state[1] > 0) {
                n_state[1]--;
                if (n_state[2] <= 20) n_state[2]++;
                chmax(ndp[n_state], val);
              }
            }
            if (ch == 'O') {
              if (n_state[2] > 0) {
                n_state[2]--;
                if (n_state[3] <= 20) n_state[3]++;
                chmax(ndp[n_state], val);
              }
            }
            if (ch == 'I') {
              if (n_state[3] > 0) {
                n_state[3]--;
                chmax(ndp[n_state], val + 1);
              }
            }
        }
      }
    }
    dp.swap(ndp);
  }

  int ans = 0;
  for (auto it = dp.begin(); it != dp.end(); ++it) {
    chmax(ans, it->second);
  }
  cout << ans << endl;


  return 0;
}

int main() {

#ifdef LOCAL
  for (;!cin.eof();cin>>ws)
#endif
    main2();
  return 0;
}