/**************************************************************

    Problem:

    User: BLADEVIL

    Language: Pascal

    Result: Accepted

    Time: ms

    Memory: kb

****************************************************************/

//By BLADEVIL

var

    n, k                        :longint;

    i                           :longint;

    a                           :array[..] of longint;

    ans                         :longint;

procedure swap(var a,b:longint);

var

    c                           :longint;

begin

    c:=a; a:=b; b:=c;

end;

procedure qs(low,high:longint);

var

    i, j                        :longint;

    xx                          :longint;

begin

    i:=low; j:=high;

    xx:=a[(i+j) div ];

    while i<j do

    begin

        while a[i]>xx do inc(i);

        while a[j]<xx do dec(j);

        if i<=j then

        begin

            swap(a[i],a[j]);

            inc(i); dec(j);

        end;

    end;

    if i<high then qs(i,high);

    if j>low then qs(low,j);

end;

begin

    read(n,k);

    for i:= to k do read(a[i]);

    qs(,k);

    ans:=;

    for i:= to k do

    begin

        if n<= then break;

        ans:=ans+(n-)*a[i];

        dec(n,);

    end;

    writeln(ans);

end.