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0_0_7587496_16161.cpp: In function `std::string Da(std::string, std::string)':
0_0_7587496_16161.cpp:27: error: invalid conversion from `char' to `const char*'
0_0_7587496_16161.cpp:27: error:   initializing argument 2 of `std::basic_string<_CharT, _Traits, _Alloc>& std::basic_string<_CharT, _Traits, _Alloc>::insert(typename _Alloc::size_type, const _CharT*) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]'