program uspon;

var a,b,c,d,i,j,n:longint;
    x,y:array[1..10000] of longint;

begin

   readln(n);

     for i:=1 to n do read(x[i]);

        for i:=2 to n do begin

              repeat


                    b:=x[i]-x[i-1]+b;


                until (x[i-1] > x[i]) or (x[i-1] = x[i]);
                y[b]:=b;
                b:=0;

        end;


      for i:=1 to (n-1) do
          for j:=i+1 to n do

             if y[i] > y[j] then begin
               a:=y[i];
               y[i]:=y[j];
               y[j]:=a;

              end;

writeln(y[n]);


end.