Problem with matrix boundaries

Question

Good afternoon! I’m doing vector exercises and found a problem where I don’t understand.

The proposed problem was to place values on a vector A and B of size 5, and then merge these values into a vector C of size 10. Desse jeito: A {1,2,3,4,5} B {6,7,8,9,10} C{1,2,3,4,5,6,7,8,9,10}

However it appears that the Dice extrapolates the limits of the matrix, even if I put 800 as read as the code below.

static void Main(string[] args)
{
    int[] vetorA = new int[5];
    int[] vetorB = new int[5];
    int[] vetorC = new int[10];

   //Colocando valores no vetorA
    for (int i = 0; i < 5; i++)
    {
        vetorA[i] = int.Parse(Console.ReadLine());
    }

    //Colocando valores no vetorB
    for(int i = 0; i < 5; i++)
    {
        vetorB[i] = int.Parse(Console.ReadLine());
    }

    //Colocando os valores de vetorA em vetorC
    for(int i = 0; i < 5; i++)
    {
        vetorC[i] = vetorA[i];
    }

    //Colocando os valores de vetorB juntamente com vetorA no vetorC
    for(int j = 0; j < 5; j++)
    {
        vetorC[j + 5] = vetorB[j];
    }

    //lendo e imprimindo os valores do vetorC completo
    for(int x = 0; x < 800; x++)
    {
        Console.WriteLine(vetorC[x]);
    }


    Console.ReadLine();

}