/in/foo.cc: In function 'int main()':
/in/foo.cc:62:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (long long i=1;i<=n;i++)
                     ~^~~
/in/foo.cc:71:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (long long i=2;i<=k+1;i++)
                     ~^~~~~