/in/foo.cc: In function 'int main()':
/in/foo.cc:27:25: warning: iteration 20000 invokes undefined behavior [-Waggressive-loop-optimizations]
         while (horizon[i] > 1) {
                ~~~~~~~~~^
/in/foo.cc:25:28: note: within this loop
     for (int i = OFFSET; i <= OFFSET + 20000; i++) {
                          ~~^~~~~~~~~~~~~~~~~