foo.cc: In function 'int main()':
foo.cc:9:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s.size();i++)
              ~^~~~~~~~~
foo.cc:11:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(s[i]==' '&&s[i+1]!=' '&&i+1<s.size())
                              ~~~^~~~~~~~~
foo.cc:14:37: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
    while(s[end+1]!=' '&&('a'<=s[end]&&s[end]<='z'||'A'<=s[end]&&s[end]<='Z'))
                          ~~~~~~~~~~~^~~~~~~~~~~~~
foo.cc:26:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<s.size()-1;i++)
              ~^~~~~~~~~~~

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