using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
		
		int N=S.Length;
		int[][][][] dp=new int[21][][][];
		for(int i=0;i<21;i++){
			dp[i]=new int[21][][];
			for(int j=0;j<21;j++){
				dp[i][j]=new int[21][];
				for(int k=0;k<21;k++){
					dp[i][j][k]=new int[21];
					for(int l=0;l<21;l++){
						dp[i][j][k][l]=-1;
					}
				}
			}
		}
		dp[0][0][0][0]=0;
		for(int c=0;c<N;c++){
			int[][][][] dnxt=new int[21][][][];
			for(int i=0;i<21;i++){
				dnxt[i]=new int[21][][];
				for(int j=0;j<21;j++){
					dnxt[i][j]=new int[21][];
					for(int k=0;k<21;k++){
						dnxt[i][j][k]=new int[21];
						for(int l=0;l<21;l++){
							dnxt[i][j][k][l]=dp[i][j][k][l];
						}
					}
				}
			}
			for(int i=0;i<21;i++){
				for(int j=0;j<21;j++){
					for(int k=0;k<21;k++){
						for(int l=0;l<21;l++){
							if(dp[i][j][k][l]==-1)continue;
							switch(S[c]){
								case 'K':if(i+1<21)dnxt[i+1][j][k][l]=Math.Max(dnxt[i+1][j][k][l],dp[i][j][k][l]);break;
								case 'U':if(j+1<21&&i-1>=0)dnxt[i-1][j+1][k][l]=Math.Max(dnxt[i-1][j+1][k][l],dp[i][j][k][l]);break;
								case 'R':if(k+1<21&&j-1>=0)dnxt[i][j-1][k+1][l]=Math.Max(dnxt[i][j-1][k+1][l],dp[i][j][k][l]);break;
								case 'O':if(l+1<21&&k-1>=0)dnxt[i][j][k-1][l+1]=Math.Max(dnxt[i][j][k-1][l+1],dp[i][j][k][l]);break;
								case 'I':if(l-1>=0)dnxt[i][j][k][l-1]=Math.Max(dnxt[i][j][k][l-1],dp[i][j][k][l]+1);break;
								case '?':
									if(i+1<21)dnxt[i+1][j][k][l]=Math.Max(dnxt[i+1][j][k][l],dp[i][j][k][l]);
									if(j+1<21&&i-1>=0)dnxt[i-1][j+1][k][l]=Math.Max(dnxt[i-1][j+1][k][l],dp[i][j][k][l]);
									if(k+1<21&&j-1>=0)dnxt[i][j-1][k+1][l]=Math.Max(dnxt[i][j-1][k+1][l],dp[i][j][k][l]);
									if(l+1<21&&k-1>=0)dnxt[i][j][k-1][l+1]=Math.Max(dnxt[i][j][k-1][l+1],dp[i][j][k][l]);
									if(l-1>=0)dnxt[i][j][k][l-1]=Math.Max(dnxt[i][j][k][l-1],dp[i][j][k][l]+1);
									break;
								default:dnxt[i][j][k][l]=dp[i][j][k][l];
									break;
							}
						}
					}
				}
			}
			for(int i=0;i<21;i++){
				for(int j=0;j<21;j++){
					for(int k=0;k<21;k++){
						for(int l=0;l<21;l++){
							dp[i][j][k][l]=dnxt[i][j][k][l];
						}
					}
				}
			}
		}
		
		int max=0;
		foreach(var a in dp)foreach(var b in a)foreach(var c in b)foreach(var x in c)max=Math.Max(max,x);
		Console.WriteLine(max);
		
		
	}
	
	
	String S;
	public Sol(){
		S=rs();
	}

	struct ATMTN{
		public int K,U,R,O,I;
		public ATMTN(int k,int u,int r,int o,int i){
			K=k;U=u;R=r;O=o;I=i;
		}
		public ATMTN(ATMTN a){
			K=a.K;U=a.U;R=a.R;O=a.O;I=a.I;
		}
	}


	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(){return Console.ReadLine().Split(' ');}
	static int[] ria(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>int.Parse(e));}
	static long[] rla(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>long.Parse(e));}
	static double[] rda(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>double.Parse(e));}
}