View Compilation Error

0_0_23915837_24034.cpp: In function 'int main()':
0_0_23915837_24034.cpp:21:26: error: could not convert 's.std::set<_Key, _Compare, _Alloc>::find<int, std::less<int>, std::allocator<int> >((*(const key_type*)(& t)))' from 'std::set<int>::iterator {aka std::_Rb_tree_const_iterator<int>}' to 'bool'
             if (s.find(t)) s.erase(t);
                          ^