foo.cc: In function 'int main()':
foo.cc:70:10: warning: iteration 26 invokes undefined behavior [-Waggressive-loop-optimizations]
   ans[i] = -1;
   ~~~~~~~^~~~
foo.cc:69:17: note: within this loop
     for(i = 0;i < 30;i++)
               ~~^~~~

自豪的采用jd5进行评测(github.com/masnn/jd5)