var n,m,rez,i,j,k,x:longint;
v,t,c:array[1..5000] of longint;
f,g:text;
begin
assign(f,'secv.in');
reset(f);
readln(f,n);
for i:=1 to n do
  begin
  read(f,v[i]);
  t[i]:=v[i];
  end;
close(f);
rez:=1000000000;
for i:=1 to n do
for j:= i+1 to n do
  if t[i]>t[j] then
     begin
     x:=t[i];
     t[i]:=t[j];
     t[j]:=x;
     end;
c[1]:=t[1];
m:=1;
for i:=2 to n do
  if t[i]<>t[i-1] then
      begin
       inc(m);
       c[m]:=t[i];
       end;
for i:=n downto 1 do
     begin
        if v[i]=c[m] then
                    begin
                    k:=i;
                    for j:=m-1 downto 1 do
                            begin
                            while (k>0) and (v[k]<>c[j]) do dec(k);
                            if (k<=0) then break;
                            end;
                    if (k>0) and(rez>i-k+1) then rez:=i-k+1;
                    end;
        end;
assign(g,'secv.out');
rewrite(g);
if rez=1000000000 then writeln(g,'-1')
else writeln(g,rez);
close(g);
end.