#include <iostream>
#include <cstring>

using namespace std;

char s[201];
int k, lg, i, ab, ai, av;

int vcar(int i);

int main() {
    while(cin.get(s, 201)) {
        lg = strlen(s);

        k = 1;
        for(i = 0;i < lg;i++) {
            k = vcar(i);
            if(k == 0) break;
            if('a' <= s[i] && 'z' >= s[i]) av++;
            if(s[i] == 'B' && (s[i + 1] == 'X' || s[i + 1] == 'P')) ab++;
            if(s[i + 1] == 'I' && (s[i] == 'S' || s[i] == 'D')) ai++;

            if(av > 1 || ab > 1 || ai > 1) {
                k = 0;
                break;
            }
        }

        if(k == 1) cout << "OK\n";
        else cout << "ERROR\n";

        cin.get();
    }
}

int vcar(int i) {
    if(s[i] == '+' || s[i] == '-') return 1;
    if(s[i] == ']' || s[i] == '[') return 1;
    if('a' <= s[i] && s[i] <= 'z') return 1;
    if('0' <= s[i] && s[i] <= '9') return 1;
    if(s[i] == 'B' || s[i] == 'P' || s[i] == 'S' || s[i] == 'I' || s[i] == 'X') return 1;
    return 0;
}