foo.cc: In function ‘int main()’:
foo.cc:6:16: warning: ‘n’ is used uninitialized [-Wuninitialized]
    6 |         while(n<=1000)
      |               ~^~~~~~
foo.cc:5:17: note: ‘n’ was declared here
    5 |         int i=1,n;
      |                 ^