foo.cc: In function 'int main()':
foo.cc:118:15: warning: 'void* memset(void*, int, size_t)' clearing an object of type 'struct bignum' with no trivial copy-assignment; use assignment or value-initialization instead [-Wclass-memaccess]
  118 |         memset(f[now^1],0,sizeof f[now^1]);
      |         ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:24:8: note: 'struct bignum' declared here
   24 | struct bignum {
      |        ^~~~~~

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