/in/foo.cc: In function 'int main()':
/in/foo.cc:7:13: warning: left operand of comma operator has no effect [-Wunused-value]
  for(i=1; ;i<n-1,i++)
            ~^~~~
/in/foo.cc:21:2: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if (n==s)
  ^~