/in/foo.cc: In function 'int main()':
/in/foo.cc:9:26: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'std::__cxx11::string* {aka std::__cxx11::basic_string<char>*}' [-Wformat=]
  scanf("%s%s",&DNA1,&DNA2);
                          ^
/in/foo.cc:9:26: warning: format '%s' expects argument of type 'char*', but argument 3 has type 'std::__cxx11::string* {aka std::__cxx11::basic_string<char>*}' [-Wformat=]
/in/foo.cc:12:27: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
      if (DNA1[i] = DNA2[i]) sum++;
                           ^