0_0_13444914_17821.c 0_0_13444914_17821.c(12) : error C2065: “cin”: 未声明的标识符 0_0_13444914_17821.c(16) : error C2065: “cout”: 未声明的标识符 0_0_13444914_17821.c(16) : error C2065: “endl”: 未声明的标识符