Mysterious Code (24h effective)

A statistical problem can occur several times each number, you need to define an array
 // key codes 
int VIS [ 10005 ]; 
Memset (VIS, 0 , the sizeof (VIS));
 for ( int I = 0 ; I < n-; I ++ ) 
{ 
    VIS [A [I]] ++ ; 
} 
for ( int I = 0 ; I <n-; I ++ ) 
{ 
    IF (VIS [I] == ???????? ) 
        the printf ( " D% \ n- " , I); 
}