foo.cc: In function 'int main()':
foo.cc:6:3: warning: statement has no effect [-Wunused-value]
  0<=a;
  ~^~~
foo.cc:7:3: warning: statement has no effect [-Wunused-value]
  b<=32767;
  ~^~~~~~~
foo.cc:9:9: error: 'o' was not declared in this scope
  return o;
         ^

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