/in/foo.cc: In function 'bool check(int)':
/in/foo.cc:9:6: error: 'd' was not declared in this scope
 a[i]=d%10;
      ^
/in/foo.cc:6:5: warning: unused variable 'dt' [-Wunused-variable]
 int dt=date,a[5],month,day;
     ^~