View Compilation Error

0_0_2210809_29137.cpp:2: error: `main' must return `int'
0_0_2210809_29137.cpp: In function `int main(...)':
0_0_2210809_29137.cpp:4: error: `scanf' undeclared (first use this function)
0_0_2210809_29137.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_2210809_29137.cpp:5: error: `printf' undeclared (first use this function)