/in/foo.cc: In function 'void update(int, int, int, int, int, int)':
/in/foo.cc:28:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
 int mid = l + r >> 1;
           ~~^~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:53:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for (int i = 0; i < events.size(); i++) {
                 ~~^~~~~~~~~~~~~~~