View Compilation Error

0_0_12814273_3734.cpp: In function `double L(double, double, double)':
0_0_12814273_3734.cpp:6: error: `sqrt' undeclared (first use this function)
0_0_12814273_3734.cpp:6: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_12814273_3734.cpp: In function `int main()':
0_0_12814273_3734.cpp:12: error: `scanf' undeclared (first use this function)
0_0_12814273_3734.cpp:17: error: `clock' undeclared (first use this function)
0_0_12814273_3734.cpp:19: error: `rand' undeclared (first use this function)
0_0_12814273_3734.cpp:25: error: `printf' undeclared (first use this function)