How do I use static class members in C++?

class Example {
public:
    static int staticValue; // Declaration of static member
    int instanceValue; // Instance member

    Example(int val) : instanceValue(val) {}

    static void setStaticValue(int val) {
        staticValue = val; // Setting value of static member
    }

    static int getStaticValue() {
        return staticValue; // Getting value of static member
    }
};

// Definition of static member
int Example::staticValue = 0;

int main() {
    Example::setStaticValue(10); // Setting static member
    Example obj1(1);
    Example obj2(2);

    std::cout << "Static Value: " << Example::getStaticValue() << std::endl; // Accessing static member
    std::cout << "Instance Value of obj1: " << obj1.instanceValue << std::endl; // Accessing instance member
    std::cout << "Instance Value of obj2: " << obj2.instanceValue << std::endl; // Accessing instance member

    return 0;
}