program bt24;
uses crt;
var A:array[1..1000,1..1000] of integer;
        i,j,k,l,m,n:integer;
        S:int64;
        F,Y:text;
procedure  khaibao;
        Begin
                clrscr;
                Assign(F,'D:\69\QUANCO.INP');
                Assign(Y,'D:\69\QUANCO.OUT');
                Reset(F);
                Rewrite(Y);
                Readln(F,m,n,i,j);

                end;

procedure DQ(x,y:integer);
Begin
      If (x<>0) and (y<>0)   then
      If (x<=m) and (Y<=n) then
      Begin

        If (x=i) and (y=j) then S:=S+1
        else
                Begin
                DQ(x+2,y-1);
                DQ(x+2,y+1);
                DQ(x+1,y+2);
                DQ(x-1,y+2);
                end;
        end;
      end;
        Begin
        khaibao;
        DQ(1,1);
        Writeln(Y,S);

 Readln;
 Close(F);
 Close(Y);
 End.