/in/foo.cc: In function 'int main()':
/in/foo.cc:29:18: warning: format '%s' expects a matching 'char*' argument [-Wformat=]
     printf("%s\n");
                  ^
/in/foo.cc:35:18: warning: format '%s' expects a matching 'char*' argument [-Wformat=]
     printf("%s\n");
                  ^