-1
When doing the division operation int / int, the language rounds down to keep the value as type int.
Contador is 49, maximum is > 49.
A division of an int by a value greater than it will always be less than 0, so the result will be rounded to 0.
Consider changing the type of variables or use a cast for double and retell the test. :)

Where
atualis declared? In this your code, the execution forwhile, thereforeatualis not performed. Post the code snippet where it is declared and where it is changed.– CypherPotato