#include <iostream>
#include <stack>
#include <string>

enum class BracketType {
    Round, Square, Curl
};

enum class Direction {
    Open, Close
};

struct Bracket {
    BracketType type;
    Direction direction;
    explicit Bracket (char charBracket) {
        if (charBracket == '(' or charBracket == '[' or charBracket == '{') {
            this->direction = Direction::Open;
        } else {
            this->direction = Direction::Close;
        }
        if (charBracket == '(' or charBracket == ')') {
            this->type = BracketType::Round;
        } else if (charBracket == '[' or charBracket == ']') {
            this->type = BracketType::Square;
        } else {
            this->type = BracketType::Curl;
        }
    }
};


int main() {
    std::ios_base::sync_with_stdio(false);
    std::stack<Bracket> brackets;
    std::string line_with_brackets;
    std::cin >> line_with_brackets;
    size_t minimal_correct = 0;
    bool correct = true;
    for (char bracket_char: line_with_brackets) {
        Bracket bracket{bracket_char};
        if (bracket.direction == Direction::Open) {
            brackets.push(bracket);
        } else if (!brackets.empty() && bracket.type == brackets.top().type) {
            brackets.pop();
        } else {
            correct = false;
            break;
        }
        ++minimal_correct;
    }
    if (correct && brackets.empty()) {
        std::cout << "CORRECT";
    } else {
        std::cout << minimal_correct;
    }
}