输入一个形如A+B的四则运算式（加、减、乘、除），代表你向计算机出的题目。让计算机输出运算结果，请按样例格式输出。如果除数为0，输出非法操作信息：Illegal operation

假设我们有一个简单的函数`calculate_expression`来计算这样的四则运算表达式，我们可以编写以下代码来完成这个任务。这里是一个C++的例子：

#include <iostream>
#include <stdexcept>

int calculate_expression(std::string expression) {
    try {
        size_t operator_pos = expression.find('+');
        if (operator_pos == std::string::npos) { // no '+' found, assume it's a number
            return std::stoi(expression); // convert to integer and return
        }

        std::string left operand = expression.substr(0, operator_pos);
        std::string right_operand = expression.substr(operator_pos + 1);

        char op = expression[op_pos]; // get the operator

        if (op == '+') {
            return std::stoi(left_operand) + std::stoi(right_operand);
        } else if (op == '-') {
            return std::stoi(left_operand) - std::stoi(right_operand);
        } else if (op == '*') {
            return std::stoi(left_operand) * std::stoi(right_operand);
        } else if (op == '/') {
            int right_value = std::stoi(right_operand);
            if (right_value == 0) {
                throw std::invalid_argument("Illegal operation: division by zero");
            }
            return std::stoi(left_operand) / right_value;
        } else {
            throw std::runtime_error("Unsupported operation: " + std::to_string(op));
        }
    } catch (const std::exception& e) {
        std::cerr << "Error: " << e.what() << std::endl;
        return 0;
    }
}

int main() {
    std::string expression;
    std::cout << "Enter an arithmetic expression (e.g., A+B): ";
    std::getline(std::cin, expression);

    int result = calculate_expression(expression);
    if (result != 0) {
        std::cout << "Result: " << result << std::endl;
    }

    return 0;
}