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0_0_5728822_1405.cpp
0_0_5728822_1405.cpp(57) : error C2593: “operator <<”不明确
        VC\include\ostream(313): 可能是“std::basic_ostream<_Elem,_Traits>::_Myt &std::basic_ostream<_Elem,_Traits>::operator <<(__int64)”
        with
        [
            _Elem=char,
            _Traits=std::char_traits<char>
        ]
        0_0_5728822_1405.cpp(12): 或       “std::ostream &operator <<(std::ostream &,BigInteger &)”
        试图匹配参数列表“(std::ostream, BigInteger)”时