View Compilation Error

0_0_36350703_9662.cpp: In member function 'void tree::pushdown(int)':
0_0_36350703_9662.cpp:76:28: error: 'mid' was not declared in this scope
             tr[u<<1].sum+=(mid-l+1)*lz;
                            ^
0_0_36350703_9662.cpp:76:32: error: 'l' was not declared in this scope
             tr[u<<1].sum+=(mid-l+1)*lz;
                                ^
0_0_36350703_9662.cpp:78:30: error: 'r' was not declared in this scope
             tr[u<<1|1].sum+=(r-mid)*lz;
                              ^