#include <stdio.h>
#include <ctype.h>

#define ARRAY_SIZE  15

int main(void)
{
    int input_phone[ARRAY_SIZE], counter;

    printf("Enter phone number: ");
    for (counter = 0; counter < ARRAY_SIZE; counter++)
    {
        scanf("%d", &input_phone[counter]);
        if (counter > ARRAY_SIZE)
        {
            printf("Too many input data\n");
            return 1;
        }
        else if (input_phone[counter] == '\n')
              {
                break;
              }
    }
    printf("In numeric form: ");
    for (counter = 0; counter < ARRAY_SIZE; counter++)
    {
        switch(toupper(input_phone[counter]))
        {
            case 'A': case 'B': case 'C':
            {
                printf("2");
                break;
            }
            case 'D': case 'E': case 'F':
            {
                printf("3");
                break;
            }
            case 'G': case 'H': case 'I':
            {
                printf("4");
                break;
            }
            case 'J': case 'K': case 'L':
            {
                printf("5");
                break;
            }
            case 'M': case 'N': case 'O':
            {
                printf("6");
                break;
            }
            case 'P': case 'Q': case 'R': case 'S':
            {
                printf("7");
                break;
            }
            case 'T': case 'U': case 'V':
            {
                printf("8");
                break;
            }
            case 'W': case 'X': case 'Y': case 'Z':
            {
                printf("9");
                break;
            }
            default:
            {
                 printf("%d", input_phone[counter]);
                 break;
            }
        }
    }
    printf("\n");
    return 0;
}