View Compilation Error

0_0_5172014_2062.cpp: In function `void convert(int, int)':
0_0_5172014_2062.cpp:7: error: `printf' undeclared (first use this function)
0_0_5172014_2062.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_5172014_2062.cpp: In function `void cha(int, int)':
0_0_5172014_2062.cpp:13: error: `printf' undeclared (first use this function)
0_0_5172014_2062.cpp: In function `int main()':
0_0_5172014_2062.cpp:22: error: `scanf' undeclared (first use this function)
0_0_5172014_2062.cpp:27: error: `system' undeclared (first use this function)