import java.io.InputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
import java.math.BigDecimal;
import java.math.BigInteger;
    
public class Main{
 
static PrintWriter out;
static InputReader ir;
static final int INF=Integer.MAX_VALUE;
static final long LINF=Long.MAX_VALUE;
 
static void solve(){
 char[] s=ir.next().toCharArray();
 int K=0;
 int U=0;
 int R=0;
 int O=0;
 int que=0;
 for(int i=0;i<s.length;i++){
  char c=s[i];
  if(c=='K') K++;
  if(c=='U') U++;
  if(c=='R') R++;
  if(c=='O') O++;
  if(c=='?') que++;
 }
 int[][][][][] dp=new int[2][K+que+1][U+que+1][R+que+1][O+que+1];
 for(int i=0;i<s.length;i++){
  for(int k=0;k<=K+que;k++){
   for(int u=0;u<=U+que;u++){
    for(int r=0;r<=R+que;r++){
     for(int o=0;o<=O+que;o++){
      if(s[i]=='K'||s[i]=='?'){
       if(k!=K+que) dp[1][k+1][u][r][o]=Math.max(dp[1][k+1][u][r][o],dp[0][k][u][r][o]);
      }
      if(s[i]=='U'||s[i]=='?'){
       if(u!=U+que) dp[1][k][u+1][r][o]=Math.max(dp[1][k][u+1][r][o],dp[0][k][u][r][o]);
      }
      if(s[i]=='R'||s[i]=='?'){
       if(r!=R+que) dp[1][k][u][r+1][o]=Math.max(dp[1][k][u][r+1][o],dp[0][k][u][r][o]);
      }
      if(s[i]=='O'||s[i]=='?'){
       if(o!=O+que) dp[1][k+1][u][r][o+1]=Math.max(dp[1][k][u][r][o+1],dp[0][k][u][r][o]);
      }
      if(s[i]=='I'||s[i]=='?'){
       if(k>0&&u>0&&r>0&&o>0) dp[1][k-1][u-1][r-1][o-1]=Math.max(dp[1][k-1][u-1][r-1][o-1],dp[0][k][u][r][o]+1);
      }
     }
    }
   }
  }
  for(int k=0;k<=K+que;k++){
   for(int u=0;u<=U+que;u++){
    for(int r=0;r<=R+que;r++){
     for(int o=0;o<=O+que;o++){
      dp[0][k][u][r][o]=dp[1][k][u][r][o];
     }
    }
   }
  }
 }
 int ans=0;
 for(int k=0;k<=K+que;k++){
  for(int u=0;u<=U+que;u++){
   for(int r=0;r<=R+que;r++){
    for(int o=0;o<=O+que;o++){
     ans=Math.max(ans,dp[0][k][u][r][o]);
     }
    }
   }
  }
 out.println(ans);
}

public static void main(String[] args) throws Exception{
 ir=new InputReader(System.in);
 out=new PrintWriter(System.out);
 solve();
 out.flush();
}

static class InputReader {
 private InputStream in;
 private byte[] buffer=new byte[1024];
 private int curbuf;
 private int lenbuf;

 public InputReader(InputStream in) {this.in=in; this.curbuf=this.lenbuf=0;}
 
 public boolean hasNextByte() {
  if(curbuf>=lenbuf){
   curbuf= 0;
   try{
    lenbuf=in.read(buffer);
   }catch(IOException e) {
    throw new InputMismatchException();
   }
   if(lenbuf<=0) return false;
  }
  return true;
 }

 private int readByte(){if(hasNextByte()) return buffer[curbuf++]; else return -1;}
 
 private boolean isSpaceChar(int c){return !(c>=33&&c<=126);}
 
 private void skip(){while(hasNextByte()&&isSpaceChar(buffer[curbuf])) curbuf++;}
 
 public boolean hasNext(){skip(); return hasNextByte();}
 
 public String next(){
  if(!hasNext()) throw new NoSuchElementException();
  StringBuilder sb=new StringBuilder();
  int b=readByte();
  while(!isSpaceChar(b)){
   sb.appendCodePoint(b);
   b=readByte();
  }
  return sb.toString();
 }
 
 public int nextInt() {
  if(!hasNext()) throw new NoSuchElementException();
  int c=readByte();
  while (isSpaceChar(c)) c=readByte();
  boolean minus=false;
  if (c=='-') {
   minus=true;
   c=readByte();
  }
  int res=0;
  do{
   if(c<'0'||c>'9') throw new InputMismatchException();
   res=res*10+c-'0';
   c=readByte();
  }while(!isSpaceChar(c));
  return (minus)?-res:res;
 }
 
 public long nextLong() {
  if(!hasNext()) throw new NoSuchElementException();
  int c=readByte();
  while (isSpaceChar(c)) c=readByte();
  boolean minus=false;
  if (c=='-') {
   minus=true;
   c=readByte();
  }
  long res = 0;
  do{
   if(c<'0'||c>'9') throw new InputMismatchException();
   res=res*10+c-'0';
   c=readByte();
  }while(!isSpaceChar(c));
  return (minus)?-res:res;
 }
 
 public double nextDouble(){return Double.parseDouble(next());}
 
 public BigInteger nextBigInteger(){return new BigInteger(next());}
 
 public BigDecimal nextBigDecimal(){return new BigDecimal(next());}
 
 public int[] nextIntArray(int n){
  int[] a=new int[n];
  for(int i=0;i<n;i++) a[i]=nextInt();
  return a;
 }
 
 
 public long[] nextLongArray(int n){
  long[] a=new long[n];
  for(int i=0;i<n;i++) a[i]=nextLong();
  return a;
 }

 public char[][] nextCharMap(int n,int m){
  char[][] map=new char[n][m];
  for(int i=0;i<n;i++) map[i]=next().toCharArray();
  return map;
 }
}
}