not repeated serial number in c
#include <stdio.h>
int main()
{
int a, b, c;
for (a = 1; a <= 3; a++) {
for (b = 1; b <= 3 && b != a; b++) {
for (c = 1; c <= 3 && c != a && c != b; c++) {
printf ("%d, %d, %d\n", a, b, c);
}
}
}
return 0;
}