#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define vector4d(type,name,h,w,d,...) vector<vector<vector<vector<type>>>>name(h,vector<vector<vector<type>>>(w,vector<vector<type>>(d,vector<type>(__VA_ARGS__))))

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    string s;
    cin >> s;
    int n = s.size();
    vector4d(int,dp,21,21,21,21,-(1<<30));
    dp[0][0][0][0] = 0;
    for(int i = 0; i < n; i++){
        vector4d(int,ndp,21,21,21,21,-(1<<30));
        if(s[i] == '?'){
            for(int a = 0; a <= 20; a++){
                for(int b = 0; b <= a; b++){
                    for(int c = 0; c <= b; c++){
                        for(int d = 0; d <= c; d++){
                            ndp[a][b][c][d] = max(ndp[a][b][c][d], dp[a][b][c][d]);
                            if(a + 1 <= 20)ndp[a + 1][b][c][d] = max(ndp[a + 1][b][c][d], dp[a][b][c][d]);
                            if(b + 1 <= a)ndp[a][b + 1][c][d] = max(ndp[a][b + 1][c][d], dp[a][b][c][d]);
                            if(c + 1 <= b)ndp[a][b][c + 1][d] = max(ndp[a][b][c + 1][d], dp[a][b][c][d]);
                            if(d + 1 <= c)ndp[a][b][c][d + 1] = max(ndp[a][b][c][d + 1], dp[a][b][c][d]);
                            if(d >= 1)ndp[a-1][b-1][c-1][d-1] = max(ndp[a-1][b-1][c-1][d-1],dp[a][b][c][d]+1);
                        }
                    }
                }
            }
        }else{
            for(int a = 0; a <= 20; a++){
                for(int b = 0; b <= a; b++){
                    for(int c = 0; c <= b; c++){
                        for(int d = 0; d <= c; d++){
                            ndp[a][b][c][d] = max(ndp[a][b][c][d], dp[a][b][c][d]);
                            if(s[i] == 'K' && a + 1 <= 20)ndp[a + 1][b][c][d] = max(ndp[a + 1][b][c][d], dp[a][b][c][d]);
                            if(s[i] == 'U' && b + 1 <= a)ndp[a][b + 1][c][d] = max(ndp[a][b + 1][c][d], dp[a][b][c][d]);
                            if(s[i] == 'R' && c + 1 <= b)ndp[a][b][c + 1][d] = max(ndp[a][b][c + 1][d], dp[a][b][c][d]);
                            if(s[i] == 'O' && d + 1 <= c)ndp[a][b][c][d + 1] = max(ndp[a][b][c][d + 1], dp[a][b][c][d]);
                            if(s[i] == 'I' && d >= 1)ndp[a-1][b-1][c-1][d-1] = max(ndp[a-1][b-1][c-1][d-1],dp[a][b][c][d]+1);
                        }
                    }
                }
            }
        }
        swap(dp, ndp);
    }
    int ans = 0;
    for(int a = 0; a <= 20; a++){
        for(int b = 0; b <= a; b++){
            for(int c = 0; c <= b; c++){
                for(int d = 0; d <= c; d++){
                    ans = max(ans, dp[a][b][c][d]);
                }
            }
        }
    }
    cout << ans << '\n';
}