/in/foo.cc: In function 'int main()':
/in/foo.cc:9:7: warning: iteration 1004 invokes undefined behavior [-Waggressive-loop-optimizations]
   a[i]=0;
   ~~~~^~
/in/foo.cc:8:11: note: within this loop
  for(i=1;i<=1005;i++){
          ~^~~~~~
/in/foo.cc:19:9: warning: iteration 1004 invokes undefined behavior [-Waggressive-loop-optimizations]
   if(a[i]==1)
      ~~~^
/in/foo.cc:18:11: note: within this loop
  for(i=1;i<=1005;i++){
          ~^~~~~~