int main()
{
int a[] = {1 , 2 , 3, 1 };
int n = sizeof (a )/ sizeof(a[0]);
int i;
for ( i = 0; i < n; i++ )
{
if ( a[i] == a[(i+1)%n ] || a[i] == a[(i+2)%n] )
{
printf("%d ", a[i] );
break;
}
}
getch();
return 0;
}