View Compilation Error

In file included from 0_0_27762008_15751.cpp:2:0:
0_0_27762008_15751.cpp: In function 'void update_area(int, int, int, int)':
0_0_27762008_15751.cpp:154:9: error: 't_l' was not declared in this scope
  assert(t_l==tree[i].l);
         ^
0_0_27762008_15751.cpp:155:9: error: 't_r' was not declared in this scope
  assert(t_r==tree[i].r);
         ^