View Compilation Error

0_0_31745079_19270.cpp: In function 'void Update(int, int, int, int)':
0_0_31745079_19270.cpp:41:8: error: 'm' was not declared in this scope
  if(l<=m)Update(rt<<1,l,r,flag);
        ^
0_0_31745079_19270.cpp:42:5: error: 'm' was not declared in this scope
  if(m<r)Update(rt<<1|1,l,r,flag);
     ^