an error that i don't understand on c++ : So this is my code

    #include "stdafx.h"
    #include <iostream>
    #include <cmath>

    using namespace std;

    int main()
    {
	    int kol=0, x;

	cout << "Insert a number: ";
	cin >> x;

	while (x > 0);
	{
		div_t output;
		output = x;
		x = div(output, 10);
		kol += kol;
	}
	cout << "Amount: " << kol << endl;
	system ("pause");
	return 0;
    }

and i got this error
Error	1	error C2679: binary '=' : no operator found which takes a right-hand operand of type 'int' (or there is no acceptable conversation)

can someone tell me what i did wrong and how to fix?