View Compilation Error

2_15840_1099372_18085.cpp: In function `int main()':
2_15840_1099372_18085.cpp:13: error: `scanf' undeclared (first use this function)
2_15840_1099372_18085.cpp:13: error: (Each undeclared identifier is reported only once for each function it appears in.)
2_15840_1099372_18085.cpp:15: error: `abs' undeclared (first use this function)
2_15840_1099372_18085.cpp:15: error: `printf' undeclared (first use this function)