View Compilation Error

0_0_15511716_26199.cpp: In function 'void Update(long long int, long long int, long long int)':
0_0_15511716_26199.cpp:44:32: error: 'struct Node' has no member named 'mid'
         Update(2*rt,l,tree[rt].mid());
                                ^
0_0_15511716_26199.cpp:46:32: error: 'struct Node' has no member named 'mid'
         Update(2*rt+1,tree[rt].mid()+1,r);
                                ^