public static void Main(string[] args)
{
int k = 0;
int n = 0;
double pi = 0.0;
Console.WriteLine("Digite o valor de N:");
n = int.Parse(Console.ReadLine());
while(k <= n){
if(k % 2 == 0)
{
pi = (pi + 1)/(2*k+1);
}else
{
pi = (pi - 1)/(2*k+1);
}
k -= 1;
}
pi = 4 * pi;
Console.WriteLine("O valor de pi e:"+pi);
}