foo.cc: In function 'int main()':
foo.cc:121:21: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  121 |   if(str[i].length()!=m+1) vis[i]=0;
      |      ~~~~~~~~~~~~~~~^~~~~
foo.cc:112:6: warning: unused variable 'a' [-Wunused-variable]
  112 |  int a,b,c,d;
      |      ^
foo.cc:112:8: warning: unused variable 'b' [-Wunused-variable]
  112 |  int a,b,c,d;
      |        ^
foo.cc:112:10: warning: unused variable 'c' [-Wunused-variable]
  112 |  int a,b,c,d;
      |          ^
foo.cc:112:12: warning: unused variable 'd' [-Wunused-variable]
  112 |  int a,b,c,d;
      |            ^
foo.cc: In function 'char check1(int, int)':
foo.cc:36:1: warning: control reaches end of non-void function [-Wreturn-type]
   36 | }
      | ^

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