#include<stdio.h>
#include<math.h>
#include<cs50.h>

int main (void)
{

    int sum = 0;
    int q;
    int p;
    long long cc_number;
    int a;
    do
    {
        printf("Enter your credit card number: ");
        cc_number = get_long_long();
    }while (cc_number <0);

    for (long long i=100; i<=pow(10,17); i=i*100)
    {
        q=(cc_number%i)*10/i ;
        q=q*2;
        if (q>9)
        {
            q = (q/10)+(q%10);
        }

        sum = sum + q;
    }
    for(long long i=10; i<=pow(10,16); i=i*100)
    {
        p=(cc_number%i)*10/i;
        sum = sum + p;
    }
    if(sum%10 ==0){
        if(cc_number/pow(10,13) ==34)
        {
            printf("The card is an American Express' card\n");
        }
        else if(cc_number/pow(10,13)==37)
        {
             printf("The card is an American Express' card\n");
        }
        else if (cc_number/pow(10,14)==51)
        {
            printf("The card is a MasterCard's card\n");
        }
        else if (cc_number/pow(10,14)==52)
        {
            printf("The card is a MasterCard's card\n");
        }
        else if (cc_number/pow(10,14)==53)
        {
            printf("The card is a MasterCard's card\n");
        }
        else if (cc_number/pow(10,14)==54)
        {
            printf("The card is a MasterCard's card\n");
        }
        else if (cc_number/pow(10,14)==55)
        {
            printf("The card is a MasterCard's card\n");
        }
        else if (cc_number/pow(10,15)==4)
        {
            printf("The card is a Visa's card\n");
        }
         else if (cc_number/pow(10,14)==4)
        {
            printf("The card is a Visa's card\n");
        }
         else if (cc_number/pow(10,13)==4)
        {
            printf("The card is a Visa's card\n");
        }
         else if (cc_number/pow(10,12)==4)
        {
            printf("The card is a Visa's card\n");
        }
        else
        {
            printf("The card is fake...\n");
        }
    }
    else
    {
            printf("The card is invalid...\n");
    }
}