/in/foo.cc:49:9: warning: #pragma once in main file
 #pragma once
         ^~~~
/in/foo.cc: In function 'std::__cxx11::string reads()':
/in/foo.cc:91:15: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  while (c>='a'&&c<='z'||c>='A'&&c<='Z') s+=c,c=getchar();
         ~~~~~~^~~~~~~~