import java.util.Arrays;
import java.util.Scanner;


public class Main_yukicoder291 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        char[] s = sc.next().toCharArray();
        int n = s.length;

        int[][][][][] dp = new int[2][20 + 1][20 + 1][20 + 1][20 + 1];
        for (int i = 0; i < 2; i++) {
    	for (int jk = 0; jk <= 20; jk++) {
        	for (int ju = 0; ju <= 20; ju++) {
            	for (int jr = 0; jr <= 20; jr++) {
//                	for (int jo = 0; jo <= 20; jo++) {
                		Arrays.fill(dp[i][jk][ju][jr], -1);
//                	}
            	}
        	}
    	}
        }
    	dp[0][0][0][0][0] = 0;

    	int ret = 0;
        for (int i = 0; i < n; i++) {
        	int now = i % 2;
        	int next = (i + 1) % 2;
        	for (int jk = 0; jk <= 20; jk++) {
            	for (int ju = 0; ju <= 20; ju++) {
                	for (int jr = 0; jr <= 20; jr++) {
                    	for (int jo = 0; jo <= 20; jo++) {
                    		int d = dp[now][jk][ju][jr][jo];
                    		if (d < 0) {
                    			continue;
                    		}

                    		dp[next][jk][ju][jr][jo] = Math.max(dp[next][jk][ju][jr][jo], d);
                    		if ((s[i] == 'K' || s[i] == '?') && jk < 20) {
                    			dp[next][jk + 1][ju][jr][jo] = Math.max(dp[next][jk + 1][ju][jr][jo], d);
                    		}
                    		if ((s[i] == 'U' || s[i] == '?') && ju < 20 && jk > 0) {
                    			dp[next][jk - 1][ju + 1][jr][jo] = Math.max(dp[next][jk - 1][ju + 1][jr][jo], d);
                    		}
                    		if ((s[i] == 'R' || s[i] == '?') && jr < 20 && ju > 0) {
                    			dp[next][jk][ju - 1][jr + 1][jo] = Math.max(dp[next][jk][ju - 1][jr + 1][jo], d);
                    		}
                    		if ((s[i] == 'O' || s[i] == '?') && jo < 20 && jr > 0) {
                    			dp[next][jk][ju][jr - 1][jo + 1] = Math.max(dp[next][jk][ju][jr - 1][jo + 1], d);
                    		}
                    		if ((s[i] == 'I' || s[i] == '?') && jo > 0) {
                    			dp[next][jk][ju][jr][jo - 1] = Math.max(dp[next][jk][ju][jr][jo - 1], d + 1);
                    			ret = Math.max(ret, dp[next][jk][ju][jr][jo - 1]);
                    		}
                    	}
                	}
            	}
        	}
        }

        System.out.println(ret);

        sc.close();
    }
}