/in/foo.cc: In function 'int main()':
/in/foo.cc:22:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0; j < strlen(a); j ++)
                   ~~^~~~~~~~~~~
/in/foo.cc:79:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if (j != strlen(a) - 1) cout << ' ';
        ~~^~~~~~~~~~~~~~~~