foo.cc: In function 'void update(int, int, int, int, int, int)':
foo.cc:33:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   33 | int mid = l + r >> 1;
      |           ~~^~~
foo.cc: In function 'int main()':
foo.cc:59:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Line>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   59 | for (int i = 0; i < events.size(); i++) {
      |                 ~~^~~~~~~~~~~~~~~
foo.cc:40:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   40 | scanf("%d%d%d%d%d", &n, &f, &a, &b, &k);
      | ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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