---

Lỗi biên dịch:

Main.cc: In function ‘int check(char*, long long int)’:
Main.cc:12:4: error: ‘dem’ was not declared in this scope
    dem++;
    ^~~
Main.cc:12:4: note: suggested alternative: ‘dem3’
    dem++;
    ^~~
    dem3
Main.cc: In function ‘int main()’:
Main.cc:41:8: warning: ‘char* gets(char*)’ is deprecated [-Wdeprecated-declarations]
  gets(a);
        ^
In file included from /usr/include/stdio.h:862:0,
                 from Main.cc:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:232:1: note: declared here
 gets (char *__str)
 ^~~~
Main.cc:41:6: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result]
  gets(a);
  ~~~~^~~