View Compilation Error

0_0_39054692_826.cpp: In function 'int main()':
0_0_39054692_826.cpp:16:9: error: 'scanf' was not declared in this scope
   16 |         scanf("%d",&n);
      |         ^~~~~
0_0_39054692_826.cpp:20:17: error: 'printf' was not declared in this scope
   20 |                 printf("%d\n",f[val]);
      |                 ^~~~~~
0_0_39054692_826.cpp:2:1: note: 'printf' is defined in header '<cstdio>'; did you forget to '#include <cstdio>'?
    1 | #include<math.h>
  +++ |+#include <cstdio>
    2 | int f[21];