/in/foo.cc: In function 'bool cmp(std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:18:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<min(x.sz,y.sz);i++)
                 ~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:31:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<t.sz;i++) vis[t[i]-'a']=i;
                  ^