/in/foo.cc: In function 'int main()':
/in/foo.cc:12:9: error: 'n578124' was not declared in this scope
         n578124
         ^~~~~~~
/in/foo.cc:22:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < digits.size(); i++)
                     ~~^~~~~~~~~~~~~~~