package no291;

import java.util.HashMap;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		s = sc.next().toCharArray();
		n = s.length;
		System.out.println(dfs(0,0,0,0,0));
	}

	static int n ;
	static char[] s;
	static HashMap<Long,Integer> hm = new HashMap<>();
	public static int dfs(int i,int U,int R,int O,int I) {
		if (i == n) {
			return 0;
		}
		long h = i + U * 101 + R * 101 * 101 + O * 101 * 101 * 101 + (long) I * 101 * 101 * 101 * 101;
		Integer memo = hm.get(h);
		if (memo != null) {
			return memo;
		}
		int ret = 0;
		if (s[i] != 'K' && s[i] != 'U' && s[i] != 'R' && s[i] != 'O' && s[i] != 'I' && s[i] != '?') {
			ret = Math.max(ret,dfs(i+1,U,R,O,I));
		}
		if ((s[i] == 'K' || s[i] == '?')) {
			ret = Math.max(ret,dfs(i+1,U+1,R,O,I));
		}
		if ((s[i] == 'U' || s[i] == '?') && U > 0) {
			ret = Math.max(ret,dfs(i+1,U-1,R+1,O,I));
		}
		if ((s[i] == 'R' || s[i] == '?') && R > 0) {
			ret = Math.max(ret,dfs(i+1,U,R-1,O+1,I));
		}
		if ((s[i] == 'O' || s[i] == '?') && O > 0) {
			ret = Math.max(ret,dfs(i+1,U,R,O-1,I+1));
		}
		if ((s[i] == 'I' || s[i] == '?') && I > 0) {
			ret = Math.max(ret,dfs(i+1,U,R,O,I-1) + 1);
		}
		hm.put(h,ret);

		return ret;
	}
}