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0_0_25854051_4770.cpp
0_0_25854051_4770.cpp(31) : error C2668: “sqrt”: 对重载函数的调用不明确
        VC2013\INCLUDE\math.h(1251): 可能是“long double sqrt(long double) throw()”
        VC2013\INCLUDE\math.h(1135): 或       “float sqrt(float) throw()”
        VC2013\INCLUDE\math.h(521): 或       “double sqrt(double)”
        尝试匹配参数列表“(long)”时
0_0_25854051_4770.cpp(31) : fatal error C1903: 无法从以前的错误中恢复；正在停止编译