View Compilation Error

0_0_17234191_11020.cpp: In function 'int main()':
0_0_17234191_11020.cpp:43:44: error: 'x' was not declared in this scope
   for(int j = 1; j <= m; ++j) scanf("%d", &x), q.insert(x);
                                            ^
0_0_17234191_11020.cpp:46:27: error: could not convert 'q.std::set<_Key, _Compare, _Alloc>::find<int, std::less<int>, std::allocator<int> >((* &(a[j] - a[i])))' from 'std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}' to 'bool'
     if(q.find(a[j] - a[i])) ok[i][j] = 1;
                           ^