/in/foo.cc: In function 'int main()':
/in/foo.cc:6:11: warning: 'n' is used uninitialized in this function [-Wuninitialized]
  for(i=0;i<n;i++) a[i]=i+1;
          ~^~
/in/foo.cc:15:9: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<y;
         ^