/GOMIN - Gỡ mìn (OLP Không chuyên 2010)

              Uses Crt;
        Var n,t,k,i:longint; a:array[1..100000] of longint;
        Begin
            readln(n,t);
            for i:=1 to n do read(a[i]);
            readln(k);
            if (a[k]-a[1]<=t) or (a[n]-a[k]<=t) then writeln(a[n]-a[1]) else 
            if ((a[k]-a[1])+(a[n]-a[1]))<=((a[n]-a[k])+(a[n]-a[1]))
             then writeln((a[k]-a[1])+(a[n]-a[1])) else
                  writeln((a[n]-a[k])+(a[n]-a[1]));
            readln;
        End.