/in/foo.cc: In function 'void init()':
/in/foo.cc:30:7: warning: iteration 500009 invokes undefined behavior [-Waggressive-loop-optimizations]
   p[i]=p[i-1]*P;
       ^
/in/foo.cc:29:15: note: within this loop
  for(int i=1;i<=N;i++)
               ^