/in/foo.cc: In function 'int main()':
/in/foo.cc:30:92: warning: format '%d' expects argument of type 'int', but argument 2 has type 'LL {aka long long int}' [-Wformat=]
  printf("%I64d\n", ((LL) b * inv(c, a) % a * c + (LL) d * inv(a, c) % c * a) % ((LL) a * c));
                                                                                            ^