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0_0_22243913_22631.cpp: In function 'int main()':
0_0_22243913_22631.cpp:122:24: error: conversion from 'std::set<std::basic_string<char> >::iterator {aka std::_Rb_tree_const_iterator<std::basic_string<char> >}' to non-scalar type 'std::string {aka std::basic_string<char>}' requested
   string tmp = s.begin();
                        ^