View Compilation Error

0_0_7873638_3788.cpp: In function `int main()':
0_0_7873638_3788.cpp:21: error: `scanf' undeclared (first use this function)
0_0_7873638_3788.cpp:21: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_7873638_3788.cpp:23: error: `memset' undeclared (first use this function)
0_0_7873638_3788.cpp:37: error: `printf' undeclared (first use this function)