How to printf a upside down star pyramid in C

Here’s my approach to this beginner problem. Nested loops are used to format the pyramids print structure. This problem is basically taught to get students used to basic nested loops.

#include <stdio.h>

int main()
{
    int input;
    do {
        printf("ODD input please: ");
        scanf("%d",&input);
    }
    while (input%2==0);


    int x;
    for(x=input;x>0;x=x-2)
    {
        printf("\t\t\t");
        int j=input-x;;
        while(j>0)
            {
        printf(" ");
            j=j-2;
            }

        int i;
        for(i=x;i>0;i=i-1)
            {
        printf("*");
            }
        printf("\n");
    }

    return 0;
}

The gist is hosted here: https://gist.github.com/2161158a9e2ee06a1eda