Operator Overloading for unary(-) operator

This is the solution that decreases an integer value by 1 by overloaded operator (T.U. 2071)

#include <iostream>

using namespace std;

class decrement
{
    int a;
public:
    decrement()
    {
        a=0;
    }
    decrement(int x)
    {
        a=x;
    }
    operator--(int)
    {
        a--;
    }
    operator--()
    {
        --a;
    }
    void print();
};

void decrement::print()
{
    cout << endl << "a=" << a << endl ;
}

int main()
{
    decrement d1(4);
    d1.print();
    d1--;
    d1.print();
    decrement d2(100);
    d2.print();
    --d2;
    d2.print();
    return 0;
}