package contest;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Q622 {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		char[] s = ns().toCharArray();
		int[][][][] pre = new int[21][21][21][21];
		int[][][][] cur = new int[21][21][21][21];
		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++){
						pre[i][j][k][l] = -999999;
					}
				}
			}
		}
		pre[0][0][0][0] = 0;
		for(char c : s){
			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++){
							cur[i][j][k][l] = -999999;
						}
					}
				}
			}
			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(pre[i][j][k][l] < 0)continue;
							if(c == 'K' || c == '?'){
								int ni = Math.min(i+1, 20);
								cur[ni][j][k][l] = Math.max(cur[ni][j][k][l], pre[i][j][k][l]);
							}
							if((c == 'U' || c == '?') && i >= 1){
								int nj = Math.min(j+1, 20);
								cur[i-1][nj][k][l] = Math.max(cur[i-1][nj][k][l], pre[i][j][k][l]);
							}
							if((c == 'R' || c == '?') && j >= 1){
								int nk = Math.min(k+1, 20);
								cur[i][j-1][nk][l] = Math.max(cur[i][j-1][nk][l], pre[i][j][k][l]);
							}
							if((c == 'O' || c == '?') && k >= 1){
								int nl = Math.min(l+1, 20);
								cur[i][j][k-1][nl] = Math.max(cur[i][j][k-1][nl], pre[i][j][k][l]);
							}
							if((c == 'I' || c == '?') && l >= 1){
								cur[i][j][k][l-1] = Math.max(cur[i][j][k][l-1], pre[i][j][k][l] + 1);
							}
							cur[i][j][k][l] = Math.max(cur[i][j][k][l], pre[i][j][k][l]);
						}
					}
				}
			}
			int[][][][] dum = pre; pre = cur; cur = dum;
		}
		
		int max = 0;
		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++){
						max = Math.max(max, pre[i][j][k][l]);
					}
				}
			}
		}
		out.println(max);
	}
	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
	}
	
	public static void main(String[] args) throws Exception { new Q622().run(); }
	
	private byte[] inbuf = new byte[1024];
	private int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}