foo.cc: In function 'int wdfg(char*, char*, int, int)':
foo.cc:14:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
foo.cc: In function 'int main()':
foo.cc:32:10: warning: unused variable 'n1' [-Wunused-variable]
  int num,n1,n2,l,k,n;
          ^~
foo.cc:37:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&x);
   ~~~~~^~~~~~~~~
foo.cc:57:6: warning: 'num' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<num;
  ~~~~^~~~~

[Hydro](https://hydro.ac)提供评测服务