foo.cpp: In function 'int judge(int)':
foo.cpp:11:8: warning: unused variable 'w' [-Wunused-variable]
  int i,w=0;
        ^
foo.cpp: In function 'int bin()':
foo.cpp:28:28: error: 'abs' was not declared in this scope
   if(mid==1 ) {return abs(k);}
                            ^
foo.cpp:30:21: error: 'abs' was not declared in this scope
            if(abs(ff)>=abs(k))
                     ^
foo.cpp:36:18: error: 'abs' was not declared in this scope
         if(abs(ff)>=abs(k))
                  ^
foo.cpp:43:14: error: 'abs' was not declared in this scope
  return abs(k);
              ^
foo.cpp: In function 'int main()':
foo.cpp:49:27: warning: format '%d' expects argument of type 'int*', but argument 4 has type 'long long int*' [-Wformat=]
  scanf("%d %d %d",&a,&b,&c);
                           ^
foo.cpp:48:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j,m,n;
        ^
foo.cpp: In function 'int bin()':
foo.cpp:45:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^