Console.Write("write a number: ");
double num = Int32.Parse(Console.ReadLine());
double sum = 0;
while (num != 0)
{
Console.Write("write a number: ");
num = Int32.Parse(Console.ReadLine());
if (num > 0)
{
sum = num + num;
}
}
Console.Write("sum= " + sum);
Console.ReadKey();