View Compilation Error

0_0_25925406_18507.cpp
0_0_25925406_18507.cpp(16) : error C3861: “scanf”:  找不到标识符
0_0_25925406_18507.cpp(19) : error C3861: “scanf”:  找不到标识符
0_0_25925406_18507.cpp(20) : error C3861: “printf”:  找不到标识符
0_0_25925406_18507.cpp(28) : error C2084: 函数“int main(void)”已有主体
        0_0_25925406_18507.cpp(13) : 参见“main”的前一个定义