#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
signed main(){
  string s;
  cin>>s;
  int n=s.size();
  using T = tuple<int, int, int, int>;
  vector<map<T, int> > dp(n+1);
  dp[0][T(0,0,0,0)]=0;
  for(int i=0;i<n;i++){
    for(auto p:dp[i]){
      T t=p.first;
      int res=p.second;
      int a,b,c,d;
      tie(a,b,c,d)=t;
      chmax(dp[i+1][T(a,b,c,d)],res);
      
      if(s[i]=='K'||s[i]=='?'){
        chmax(dp[i+1][T(min(a+1,20),b,c,d)],res);
      }      
      if(s[i]=='U'||s[i]=='?'){
        if(a) chmax(dp[i+1][T(a-1,min(b+1,20),c,d)],res);
      }     
      if(s[i]=='R'||s[i]=='?'){
        if(b) chmax(dp[i+1][T(a,b-1,min(c+1,20),d)],res);
      }      
      if(s[i]=='O'||s[i]=='?'){
        if(c) chmax(dp[i+1][T(a,b,c-1,min(d+1,20))],res);
      }
      if(s[i]=='I'||s[i]=='?'){
        if(d) chmax(dp[i+1][T(a,b,c,d-1)],res+1);
      }
    }    
  }
  
  int ans=0;
  for(int i=0;i<=n;i++)
    for(auto p:dp[i])
      chmax(ans,p.second);
  
  cout<<ans<<endl;
  return 0;
}