#include <iostream>
#include <vector>
#include <cstdio>
#include <string>
#include <queue>
#include <algorithm>
#include <cstring>

using namespace std;

#define MAX_N 101
#define MAX_M 21

int dp[MAX_N][MAX_M][MAX_M][MAX_M][MAX_M];

string str;

void Input(){

  cin >> str;
  for(int i = 0; i < str.length();){
    if(str[i] == 'K' || 
       str[i] == 'U' || 
       str[i] == 'R' || 
       str[i] == 'O' || 
       str[i] == 'I' || 
       str[i] == '?'){
      i++;
    }
    else{
      str.erase(i, 1);
    }
  }
  
}

int Solve(){

  memset(dp, -1, sizeof(dp));

  int ret = 0;
  dp[0][0][0][0][0] = 0;

  for(int i = 0; i < str.length(); i++){
    for(int k = 0; k < MAX_M; k++){
      for(int u = 0; u < MAX_M; u++){
	for(int r = 0; r < MAX_M; r++){
	  for(int o = 0; o < MAX_M; o++){
	    if(dp[i][k][u][r][o] == -1)
	      continue;
	    dp[i+1][k][u][r][o] = max(dp[i+1][k][u][r][o],
				      dp[i][k][u][r][o]);
	    if(str[i] == 'K' || str[i] == '?'){
	      if(k + 1 < MAX_M){
		dp[i+1][k+1][u][r][o] = max(dp[i+1][k+1][u][r][o],
					    dp[i][k][u][r][o]);
	      }
	    }
	    if(str[i] == 'U' || str[i] == '?'){
	      if(u + 1 < MAX_M && k-1 >= 0){
		dp[i+1][k-1][u+1][r][o] = max(dp[i+1][k-1][u+1][r][o],
					    dp[i][k][u][r][o]);
	      }
	    }
	    if(str[i] == 'R' || str[i] == '?'){
	      if(r + 1 < MAX_M && u-1 >= 0){
		dp[i+1][k][u-1][r+1][o] = max(dp[i+1][k][u-1][r+1][o],
					    dp[i][k][u][r][o]);
	      }
	    }
	    if(str[i] == 'O' || str[i] == '?'){
	      if(o + 1 < MAX_M && r-1 >= 0){
		dp[i+1][k][u][r-1][o+1] = max(dp[i+1][k][u][r-1][o+1],
					    dp[i][k][u][r][o]);
	      }
	    }
	    if(str[i] == 'I' || str[i] == '?'){
	      if(o >= 1){
		dp[i+1][k][u][r][o-1] = max(dp[i+1][k][u][r][o-1],
					    dp[i][k][u][r][o] + 1);
	      }
	    }
	  }
	}
      }
    }
  }

  for(int k = 0; k < MAX_M; k++){
    for(int u = 0; u < MAX_M; u++){
      for(int r = 0; r < MAX_M; r++){
	for(int o = 0; o < MAX_M; o++){
	  ret = max(ret, dp[str.length()][k][u][r][o]);
	}
      }
    }
  }

  return ret;

}

int main(){

  Input();

  cout << Solve() << endl;

  return 0;

}