foo.cc: In function 'int main()':
foo.cc:3:26: warning: unnecessary parentheses in declaration of 'i' [-Wparentheses]
    3 | #define rep(i,n) for(int (i)=1;(i)<=n;++(i))
      |                          ^
foo.cc:21:2: note: in expansion of macro 'rep'
   21 |  rep(i,n)fa[i]=i,sz[i]=1;
      |  ^~~
foo.cc:3:26: warning: unnecessary parentheses in declaration of 'i' [-Wparentheses]
    3 | #define rep(i,n) for(int (i)=1;(i)<=n;++(i))
      |                          ^
foo.cc:22:2: note: in expansion of macro 'rep'
   22 |  rep(i,m){
      |  ^~~
foo.cc:3:26: warning: unnecessary parentheses in declaration of 'i' [-Wparentheses]
    3 | #define rep(i,n) for(int (i)=1;(i)<=n;++(i))
      |                          ^
foo.cc:31:2: note: in expansion of macro 'rep'
   31 |  rep(i,n){
      |  ^~~
foo.cc:36:15: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |  for(int i=0;i<v.size();++i){
      |              ~^~~~~~~~~

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