/in/foo.cc: In function 'int main()':
/in/foo.cc:14:43: warning: iteration 500000 invokes undefined behavior [-Waggressive-loop-optimizations]
  for(int i=5;i<=1000005;i+=2,temp+=4) a[i]=a[i-1]+temp,a[i+1]=a[i]+temp;
                                       ~~~~^~~~~~~~~~~~
/in/foo.cc:14:15: note: within this loop
  for(int i=5;i<=1000005;i+=2,temp+=4) a[i]=a[i-1]+temp,a[i+1]=a[i]+temp;
              ~^~~~~~~~~
/in/foo.cc:16:62: warning: iteration 499998 invokes undefined behavior [-Waggressive-loop-optimizations]
  for(int i=8;i<=1000005;i+=2,temp+=4) b[i]=b[i-1]+temp,b[i+1]=b[i]+temp;
                                                        ~~~~~~^~~~~~~~~~
/in/foo.cc:16:15: note: within this loop
  for(int i=8;i<=1000005;i+=2,temp+=4) b[i]=b[i-1]+temp,b[i+1]=b[i]+temp;
              ~^~~~~~~~~