/in/foo.cc: In function 'int main()':
/in/foo.cc:9:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s.length();i++) a[i+1]=s[i]-'A';
              ~^~~~~~~~~~~
/in/foo.cc:12:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=2;i<=s.length();i++){
              ~^~~~~~~~~~~~