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0_0_28222352_29966.cpp: In function 'int Q()':
0_0_28222352_29966.cpp:58:23: error: could not convert 'M[i].std::map<_Key, _Tp, _Compare, _Alloc>::find<int, int, std::less<int>, std::allocator<std::pair<const int, int> > >((*(const key_type*)(& z)))' from 'std::map<int, int>::iterator {aka std::_Rb_tree_iterator<std::pair<const int, int> >}' to 'bool'
   else if(M[i].find(z))ans+=M[i][z];
                       ^