import java.util.*;

public class DemoTest5 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            System.out.println(solve(in.nextLine()));
        }
    }
    private static int solve(String s){
        char[] chars = s.toCharArray();
        int count = 0;
        boolean[]  used= new boolean[chars.length];
        for (int i=0;i<chars.length;i++){
            if(chars[i] == 'M'){
                if(i-1>=0 && chars[i-1]=='I'&& !used[i - 1]) {
                    count++;
                    used[i-1] = true;
                }else if (i+1< chars.length && chars[i+1]=='I' && !used[i + 1]){
                    count++;
                    used[i+1] = true;
                }
            }
        }
        return count >0? count:-1;
    }
}