0_0_33672644_21136.cpp 0_0_33672644_21136.cpp(5) : error C2065: “cin”: 未声明的标识符 0_0_33672644_21136.cpp(6) : error C2065: “cout”: 未声明的标识符 0_0_33672644_21136.cpp(6) : error C2065: “endl”: 未声明的标识符