View Compilation Error

0_0_5471800_18251.cpp: In function `int main()':
0_0_5471800_18251.cpp:2: error: `scanf' undeclared (first use this function)
0_0_5471800_18251.cpp:2: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_5471800_18251.cpp:4: error: `printf' undeclared (first use this function)
0_0_5471800_18251.cpp:5: error: `system' undeclared (first use this function)