View Compilation Error

0_0_24622175_23339.cpp: In function 'void update(int, int, int)':
0_0_24622175_23339.cpp:34:38: error: 'Union' was not declared in this scope
     if(pos <= mid) Union(x<<1, l, mid);
                                      ^
0_0_24622175_23339.cpp:35:43: error: 'Union' was not declared in this scope
     if(pos > mid) Union((x<<1)+1, mid+1, r);
                                           ^