foo.cc: In member function 'void tree::build(int, int, int)':
foo.cc:18:28: error: no match for 'operator=' (operand types are 'tree::node' and '<brace-enclosed initializer list>')
   18 |         nd[p] = {L, R, 1, 1};
      |                            ^
foo.cc:11:12: note: candidate: 'tree::node& tree::node::operator=(const tree::node&)'
   11 |     struct node {
      |            ^~~~
foo.cc:11:12: note:   no known conversion for argument 1 from '<brace-enclosed initializer list>' to 'const tree::node&'
foo.cc:11:12: note: candidate: 'tree::node& tree::node::operator=(tree::node&&)'
foo.cc:11:12: note:   no known conversion for argument 1 from '<brace-enclosed initializer list>' to 'tree::node&&'
foo.cc:21:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   21 |         int mid = L + R >> 1;
      |                   ~~^~~
foo.cc: In member function 'void tree::modify(int, int, int, int)':
foo.cc:31:27: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   31 |         int mid = nd[p].L + nd[p].R >> 1;
      |                   ~~~~~~~~^~~~~~~~~
foo.cc: In member function 'void tree::query(int, int)':
foo.cc:45:27: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   45 |         int mid = nd[p].L + nd[p].R >> 1;
      |                   ~~~~~~~~^~~~~~~~~
foo.cc: In member function 'void tree::changeTree(int, int)':
foo.cc:60:27: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   60 |         int mid = nd[p].L + nd[p].R >> 1;
      |                   ~~~~~~~~^~~~~~~~~

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