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

string replace(string argv[1]);

int main(int argc, string argv[])
{
    if (argc == 1 || argc > 2 )
    printf ("ERROR: Please input a single command line argument\n");
    return 1;

    if (argc == 2)
    {
        string modified = replace(argv);
        printf("%s\n", modified);
    }
}

string replace(string argv[1])
{
    int length;
    length = strlen(argv[1]);

    for (int i = 0; i < length; i++)
    {
        switch (argv[1][i])
        {
            case 'a': argv[1][i] = 6;
            case 'e': argv[1][i] = 3;
            case 'i': argv[1][i] = 1;
            case 'o': argv[1][i] = 0;
        }
    }
    return argv[1];
}