string str = "31131123521";
int result = 1;
foreach (char c in str)
{
    int digit = int.Parse(c.ToString());
    result *= digit;
}
Console.WriteLine(result);

string str = "31131123521";
int result = 1;
foreach (char c in str)
{
    int digit = int.Parse(c.ToString());
    result *= digit;
}
Console.WriteLine(result);

        string wholeString = Console.ReadLine();
        string multiplicationNumbers = "";
        foreach (var letter in wholeString)
        {
            if (char.IsDigit(letter))
            {
                multiplicationNumbers += letter;
            }
        }
        Console.WriteLine(multiplicationNumbers);
        for (int i = 0; i < multiplicationNumbers.Length; i++)
        {
            
        }

        string wholeString = Console.ReadLine();
        string multiplicationNumbers = "";
        foreach (var letter in wholeString)
        {
            if (char.IsDigit(letter))
            {
                multiplicationNumbers += letter;
            }
        }
        Console.WriteLine(multiplicationNumbers);
        for (int i = 0; i < multiplicationNumbers.Length; i++)
        {
            
        }