View Compilation Error

0_0_2168453_5500.cpp: In function `void iin()':
0_0_2168453_5500.cpp:58: error: `scanf' undeclared (first use this function)
0_0_2168453_5500.cpp:58: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_2168453_5500.cpp:65: error: `strlen' undeclared (first use this function)
0_0_2168453_5500.cpp:73: error: `memset' undeclared (first use this function)
0_0_2168453_5500.cpp: In function `int main()':
0_0_2168453_5500.cpp:134: error: `stdin' undeclared (first use this function)
0_0_2168453_5500.cpp:134: error: `freopen' undeclared (first use this function)
0_0_2168453_5500.cpp:136: error: `scanf' undeclared (first use this function)
0_0_2168453_5500.cpp:140: error: `printf' undeclared (first use this function)
0_0_2168453_5500.cpp:141: error: `memset' undeclared (first use this function)