program exetasi1(input,output);
var n,i,j,position,sum0,min : integer;
a : array[1..1000000] of integer;
begin
readln(n);
for i := 1 to n do read(a[i]);
if a[1]>0 then sum0 := (a[1] + a[2])
else if a[n]<0 then sum0 := ( a[n] + a[n - 1])
else
begin
sum0 := 2*1000000000;
for i := 1 to n do
begin
if a[n]>0 then do position := a[n-1];
end;
for i := 1 to position do
begin
for j := (position + 1) to (n - 1) do
begin
if abs(a[j])<abs(a[i]) and (abs(a[j + 1]> abs(a[i]) then
begin
if abs(a[i] + a[j])< abs(a[i] + a[j + 1]) then min := abs(a[i] + a[j])
else min := abs(a[i] + a[j + 1])
end;
if abs(min)<abs(sum0) then sum0 := min
end
end
if position<=( n - 2) then
begin
if (a[position + 1] + a[position + 2])<abs(sum0) then sum0 := (a[position + 1] + a[position + 2])
end;
if position >= 3 then
begin
if abs(a[position - 1] + a[position])< abs(sum0) then sum0 := (a[position] + a[position - 1])
end
end;
writeln(sum0)
end.
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