static void Main(string[] args)
{
int a = 1,b = 2,s = 7;
double c = 2.1, d = 3.2, cd = 0;
string str = "This is a string!";
s = a + b;
cd = c *d;
str += a;
Console.WriteLine(s);
Console.WriteLine(cd);
Console.WriteLine(str);
Console.ReadKey();
}