Output printed twice instead of once

Question

My Code is:-

/* Program to store data in link list and then print all data*/

#include <stdio.h>
#include <malloc.h>
struct value
{
    char data;
    struct value *next;
};

void main(void)
{
    struct value *head, *temp;
    char i;

    head = (struct value *) malloc (sizeof(struct value));

    temp = head;
    while (temp != NULL)
    {
        printf("Enter value to store in link list Enter z to stop\n");
        scanf("%c", &i);

        temp->data = i;
        if (i == 'z')
        {
            temp->next = NULL;
        }
        else
        {
            temp->next = (struct value *) malloc (sizeof(struct value));
        }
        temp = temp->next; 
    }

    temp = head;
    while (temp != NULL)
    {
        printf("Data is %c\n", temp->data);
        temp = temp->next;
    }

}

Output:-

Enter value to store in link list Enter z to stop
a
Enter value to store in link list Enter z to stop
Enter value to store in link list Enter z to stop
b
Enter value to store in link list Enter z to stop
Enter value to store in link list Enter z to stop
c
Enter value to store in link list Enter z to stop
Enter value to store in link list Enter z to stop
z

Data is a
Data is

Data is b
Data is

Data is
c Data is

Data is
z

---

Process exited after 4.95 seconds with return value 0 Press any key to continue . . .

Please tell me why its printing one statement twice. Whats wrong with the code Thanks