program fl;
var
s:array[1..100000] of longint;
a,b,c,d,m,n,i,j,k,h,zl:longint;
procedure kuaipai(l,r:longint);
var i,j,x,y:longint;
begin
  i:=l; j:=r; x:=s[(l+r) div 2];
  repeat
    while s[i]<x do inc(i);
    while x<s[j] do dec(j);
    if i<=j then
    begin
    y:=s[i]; s[i]:=s[j]; s[j]:=y;inc(i);dec(j);
    end;
  until i>j;
  if l<j then kuaipai(l,j);
  if i<r then kuaipai(i,r);
end;
begin
assign(input,'hay4sale.in');
reset(input);
assign(output,'hay4sale.out');
rewrite(output);
read(n,m);
for a:=1 to m do
begin read(i); s[a]:=i; end;
kuaipai(1,m);
  h:=1;
repeat
begin
  zl:=s[h]+zl;
  h:=h+1;
end;
until zl>=n ;
 if zl>n then zl:=zl-s[h-1];
 write(zl);
 
 
close(input);
close(output);
end.