/in/foo.cc: In function 'int main()':
/in/foo.cc:15:9: warning: iteration 29999 invokes undefined behavior [-Waggressive-loop-optimizations]
   if(a[i]>max) max=a[i];
      ~~~^
/in/foo.cc:13:15: note: within this loop
  for(int i=1;i<=30000;i++)
              ~^~~~~~~