/in/foo.cc: In function 'bool check(std::vector<int>)':
/in/foo.cc:24:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(i=0;i<p.size()-1;++i)
         ~^~~~~~~~~~~
/in/foo.cc: In function 'void dfs(int, int)':
/in/foo.cc:35:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(i=0;i<v.size();++i)
         ~^~~~~~~~~
/in/foo.cc:41:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(i=0;i<v.size();++i)
         ~^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:60:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(i=0;i<q.size();++i)
         ~^~~~~~~~~
/in/foo.cc:56:9: warning: unused variable 'j' [-Wunused-variable]
 int n,i,j,t,s;
         ^
/in/foo.cc:56:11: warning: unused variable 't' [-Wunused-variable]
 int n,i,j,t,s;
           ^
/in/foo.cc:56:13: warning: unused variable 's' [-Wunused-variable]
 int n,i,j,t,s;
             ^