#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>

using namespace std;
typedef long long ll;

bool dp[2][22][22][22][22][22];

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    dp[0][0][0][0][0][0] = true;
    string s;
    cin >> s;
    int ans = 0;
    for(int idx = 0; idx < s.size(); idx++){
        for(int i = 0; i <= 20; i++){
            for(int j = 0; j <= 20; j++){
                for(int k = 0; k <= 20; k++){
                    for(int l = 0; l <= 20; l++){
                        for(int m = 0; m <= 20; m++){
                            dp[(idx+1)%2][i][j][k][l][m] = dp[idx%2][i][j][k][l][m];
                        }
                    }
                }
            }
        }
        for(int i = 0; i <= 20; i++){
            for(int j = 0; j <= 20; j++){
                for(int k = 0; k <= 20; k++){
                    for(int l = 0; l <= 20; l++){
                        for(int m = 0; m <= 20; m++){
                            if(!dp[idx%2][i][j][k][l][m]) continue;
                            if(s[idx] == 'K' || s[idx] == '?'){
                                dp[(idx+1)%2][i+1][j][k][l][m] = true;
                            }
                            if((s[idx] == 'U' || s[idx] == '?') && i >= 1){
                                dp[(idx+1)%2][i-1][j+1][k][l][m] = true;
                            }
                            if((s[idx] == 'R' || s[idx] == '?') && j >= 1){
                                dp[(idx+1)%2][i][j-1][k+1][l][m] = true;
                            }
                            if((s[idx] == 'O' || s[idx] == '?') && k >= 1){
                                dp[(idx+1)%2][i][j][k-1][l+1][m] = true;
                            }
                            if((s[idx] == 'I' || s[idx] == '?') && l >= 1){
                                dp[(idx+1)%2][i][j][k][l-1][m+1] = true;
                                ans = max(ans, m+1);
                            }

                        }
                    }
                }
            }
        }
    }
    cout << ans << endl;
}