{
ZADATAK: proizvod
JEZIK: pascal
}
var i,j,ind,m,s,n,p:longint;
    k:integer;
    ch:char;
    a,b,c,rez:array[1..100] of integer;
    o:array[1..100000] of integer;
    t,f:text;
begin
assign(t,'proizvod.in');
reset(t);
readln(t,n,m);
for i:=1 to n do
begin
read(t,ch);
o[i]:=ord(ch)-48;
end;
close(t);
s:=2*m;
if s>n-2 then s:=n-2;
for i:=1 to s do
begin
k:=10;
for j:=1 to n do
if o[j]<k then
          begin
          k:=o[j];
          ind:=j;
          end;
if (i mod 2)=0 then
               begin
                p:=(i+1) div 2;
                a[p]:=k;
               end
               else
               begin
                p:=(i+1) div 2;
                b[p]:=k;
               end;
o[ind]:=10;
end;
k:=10;
if s<>2*m then
begin
for i:=1 to n do
if o[i]<k then
          begin
          k:=o[i];
          ind:=i;
          end;
p:=n div 2;
if (n mod 2)=1 then b[p+1]:=k
                else a[p]:=k;
o[ind]:=10;
for i:=1 to n do
if o[i]<>10 then if (n mod 2)=1 then a[p]:=o[i]
                                 else b[p]:=o[i];
end;
ind:=0;
for i:=1 to m do
rez[i]:=0;
for i:=1 to m do
for j:=1 to m do
begin
inc(rez[i+j-1],a[i]*b[j]);
ind:=rez[i+j-1] div 10;
rez[i+j-1]:=rez[j+i-1] mod 10;
inc(rez[i+j],ind);
end;
assign(f,'proizvod.out');
rewrite(f);
for i:=m downto 1 do
write(f,rez[i]);
close(f);
end.
