/in/foo.cc: In function 'int main()':
/in/foo.cc:5:9: error: 'scanf' was not declared in this scope
    5 |         scanf("%d %d",&year,&mon);
      |         ^~~~~
/in/foo.cc:10:25: error: 'printf' was not declared in this scope
   10 |                         printf("29");
      |                         ^~~~~~
/in/foo.cc:1:1: note: 'printf' is defined in header '<cstdio>'; did you forget to '#include <cstdio>'?
  +++ |+#include <cstdio>
    1 | using namespace std;
/in/foo.cc:14:25: error: 'printf' was not declared in this scope
   14 |                         printf("28");
      |                         ^~~~~~
/in/foo.cc:14:25: note: 'printf' is defined in header '<cstdio>'; did you forget to '#include <cstdio>'?
/in/foo.cc:21:25: error: 'printf' was not declared in this scope
   21 |                         printf("31");
      |                         ^~~~~~
/in/foo.cc:21:25: note: 'printf' is defined in header '<cstdio>'; did you forget to '#include <cstdio>'?
/in/foo.cc:25:25: error: 'printf' was not declared in this scope
   25 |                         printf("30");
      |                         ^~~~~~
/in/foo.cc:25:25: note: 'printf' is defined in header '<cstdio>'; did you forget to '#include <cstdio>'?