foo.cc: In function 'bool cmp(Player, Player)':
foo.cc:23:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |         while(cur!=a.num.size() && a.num[cur]==b.num[cur])
      |               ~~~^~~~~~~~~~~~~~
foo.cc:25:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |         if(cur==a.num.size())
      |            ~~~^~~~~~~~~~~~~~

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