View Compilation Error

0_0_20975701_1660.cpp:6:7: error: 'maxn' does not name a type
 const maxn = 50000+5;
       ^
0_0_20975701_1660.cpp:11:7: error: 'maxn' was not declared in this scope
 }tree[maxn];
       ^
0_0_20975701_1660.cpp: In function 'void PushUp(int)':
0_0_20975701_1660.cpp:14:2: error: 'tree' was not declared in this scope
  tree[rt].sum = tree[rt << 1].sum + tree[rt << 1|1].sum;
  ^
0_0_20975701_1660.cpp: In function 'void Build(int, int, int)':
0_0_20975701_1660.cpp:18:2: error: 'tree' was not declared in this scope
  tree[rt].left = l;
  ^
0_0_20975701_1660.cpp: In function 'int Search(int, int, int, int, int)':
0_0_20975701_1660.cpp:32:10: error: 'tree' was not declared in this scope
   return tree[rt].sum;
          ^
0_0_20975701_1660.cpp: In function 'void Updata(int, int, int, int, int)':
0_0_20975701_1660.cpp:43:3: error: 'tree' was not declared in this scope
   tree[rt].sum += add;
   ^