var e,i,m,j,k,x:byte;
ok:boolean;
n,pp,fac:longint;
f,g:text;
begin
assign(f,'factoriale.in');reset(f);
assign(g,'factoriale.out');rewrite(g);
read(f,n);
readln(f,k);
m:=1;
fac:=1;
for i:=1 to n do
begin
read(f,x);
for j:=2 to x do fac:=fac*j;
m:=m*fac;
fac:=1;
end;
ok:=false;
for e:=1 to m do
begin
m:=m*e;
for i:=1 to m do
begin
pp:=i;
for j:=2 to k do
pp:=pp*i;
if ((pp>=m) AND (pp mod m=0)) then
begin
ok:=true;
write(g,pp div m);
break;
end;
end;
if ok=true then break;
end;
close(f);
close(g);
end.