Untitled

#include <iostream>
#include <string>

// Function to check if the string belongs to the grammar
bool checkString(const std::string& str) {
    // The string must end with a 'b'
    if (str.empty() || str.back() != 'b') {
        return false;
    }

    // Count the number of 'a' characters before the last 'b'
    size_t i = 0;
    while (i < str.length() - 1 && str[i] == 'a') {
        ++i;
    }

    // After counting 'a's, the rest of the string must be 'b' (exactly one 'b')
    return i == str.length() - 1;
}

int main() {
    std::string input;
    
    std::cout << "Enter the string to check: ";
    std::cin >> input;
    
    if (checkString(input)) {
        std::cout << "The string belongs to the grammar.\n";
    } else {
        std::cout << "The string does not belong to the grammar.\n";
    }
    
    return 0;
}