#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <stack>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;


int dp[105][21][21][21][21];

int main(){
  ios::sync_with_stdio(false);

  string S;
  cin >> S;

  rep(i,105) rep(a,21) rep(b,21) rep(c,21) rep(d,21) dp[i][a][b][c][d] = -1;
  
  int ret = 0;
  dp[0][0][0][0][0] = 0;
  
  rep(i,S.length()){
    rep(a,21) rep(b,21) rep(c,21) rep(d,21){
      int v = dp[i][a][b][c][d];
      if(v < 0) continue;
      //cout << i << " " << a << " " << b << " " << c << " " << d << "  " << v << endl;
      dp[i+1][a][b][c][d] = max(dp[i+1][a][b][c][d], dp[i][a][b][c][d]);

      if(S[i] == 'K' || S[i] == '?') if(a<20) dp[i+1][a+1][b][c][d] = max(dp[i+1][a+1][b][c][d], v);
      if(S[i] == 'U' || S[i] == '?') if(b<20 && a>0) dp[i+1][a-1][b+1][c][d] = max(dp[i+1][a-1][b+1][c][d], v);
      if(S[i] == 'R' || S[i] == '?') if(c<20 && b>0) dp[i+1][a][b-1][c+1][d] = max(dp[i+1][a][b-1][c+1][d], v);
      if(S[i] == 'O' || S[i] == '?') if(d<20 && c>0) dp[i+1][a][b][c-1][d+1] = max(dp[i+1][a][b][c-1][d+1], v);
      if(S[i] == 'I' || S[i] == '?') if(d>0){
        ret = max(ret, v+1);
        dp[i+1][a][b][c][d-1] = max(dp[i+1][a][b][c][d-1], v+1);
      }
    }
  }
  cout << ret << endl;
  
  return 0;
}