View Compilation Error

0_0_30435796_21204.cpp: In function 'int Seg::merge(int, int)':
0_0_30435796_21204.cpp:14:17: error: 'x' was not declared in this scope
 #define ls (son[x][0])
                 ^
0_0_30435796_21204.cpp:26:5: note: in expansion of macro 'ls'
     ls = merge(son[X][0], son[Y][0]);
     ^