foo.cc:18:2: error: expected unqualified-id before 'return'
  return 0;
  ^~~~~~
foo.cc:19:1: error: expected declaration before '}' token
 }
 ^
foo.cc: In function 'int main()':
foo.cc:4:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%lld%lld%lld%lld",&n,&m,&k,&x);
 ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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