foo.cc: In function 'bign& operator++(bign&, int)':
foo.cc:246:12: warning: reference to local variable 't' returned [-Wreturn-local-addr]
  246 |     return t;
      |            ^
foo.cc:244:10: note: declared here
  244 |     bign t=a;
      |          ^
foo.cc: In function 'bign& operator--(bign&, int)':
foo.cc:257:12: warning: reference to local variable 't' returned [-Wreturn-local-addr]
  257 |     return t;
      |            ^
foo.cc:255:10: note: declared here
  255 |     bign t=a;
      |          ^
foo.cc: In function 'int main()':
foo.cc:276:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  276 |     scanf("%d %s",&n,s);
      |     ~~~~~^~~~~~~~~~~~~~

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