PKU POJ 1988 Cube Stacking

#include < iostream >
#define  MaxN 30000
using   namespace  std;
typedef  struct  node
{
     int  count;
     int  parent;
     int  d;
}NODE;
NODE S[MaxN + 1 ];
void  init()
{
     for ( int  i = 1 ;i <= MaxN;i ++ )
    {
        S[i].count = 1 ;
        S[i].d = 0 ;
        S[i].parent = i;
    }
}
int  find_set( int  x)
{
     int  t = S[x].parent;
     if (S[x].parent != x)
    {
        S[x].parent = find_set(S[x].parent);
        S[x].d += S[t].d;
    }
     return  S[x].parent;
}
void  union_set( int  x, int  y)
{
    x = find_set(x);
    y = find_set(y);
    S[y].parent = x;
    S[y].d = S[x].count;
    S[x].count += S[y].count;
}
int  main()
{
     int  P,x,y;
     char  c;
    init();
    scanf( " %d " , & P);
    getchar();    
     while (P > 0 )
    {
        P -- ;
        c = getchar();
         if (c == ' M ' )
        {
            scanf( " %d%d " , & x, & y);
            union_set(x,y);
        }
         else  
        {
            scanf( " %d " , & x);
            y = find_set(x);
            printf( " %d\n " ,S[y].count - S[x].d - 1 );
        }
        getchar();
    }
     return   0 ;
}