#include <stdio.h>
#include <cs50.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>


int main(int argc, string argv[])
{
    if (argc == 2  )
        {
            int l = strlen(argv[1]);
            for (int i = 0; i < l; i++)
    {
        isdigit(argv[1][i]);
    }
        }
        else
        {
            printf("Usage: ./caesar key\n");
            return 1;
        }

    //printf("Success\n");
    int a = atoi (argv[1]);
    //printf("%i\n", a);

    string s = get_string("plaintext: ");
    printf("ciphertext: ");
    int m = strlen(s);
    for (int i = 0; i < m; i++)
    {

        if (s[i] == 90 || s[i] == 122)
        {
           s[i] = s[i] - 26;
        }
        if (isalpha(s[i]))
        {
            int p = s[i] + a;
            char c = p;
            printf("%c", c);
        }
        else
        {
            printf("%c", s[i]);
        }
    }
    printf("\n");
}