View Compilation Error

0_0_20656630_12911.cpp: In function 'int main()':
0_0_20656630_12911.cpp:4:21: error: 'scanf' was not declared in this scope
  while(scanf("%d",&n))
                     ^
0_0_20656630_12911.cpp:13:16: error: 'printf' was not declared in this scope
   printf("%d",l);
                ^