foo.cc: In function 'int main()':
foo.cc:37:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld%lld",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:41:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld%lld",&tree[i][1],&num);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:43:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%lld",&v),add(i,v);
    ~~~~~~~~~~~~~~~~^~~~~~~~~

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