View Compilation Error

0_0_11276041_10807.cpp: In function `int possible(int)':
0_0_11276041_10807.cpp:26: error: `sort' undeclared (first use this function)
0_0_11276041_10807.cpp:26: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_11276041_10807.cpp:32: error: `max' undeclared (first use this function)
0_0_11276041_10807.cpp: In function `int main()':
0_0_11276041_10807.cpp:40: error: `scanf' undeclared (first use this function)
0_0_11276041_10807.cpp:44: error: `strlen' undeclared (first use this function)
0_0_11276041_10807.cpp:60: error: `printf' undeclared (first use this function)