var
n, a, b, i, j, k, min, max: integer;
s: longint;
min1, min2: array [0..3] of longint;
begin
    readln(n);
    s := 0;
    min1[0] := 0;
    for i := 1 to 3 do
        min1[i] := 100001;
    for i := 1 to n do
    begin
        readln(a, b);
        if a > b then
        begin
            max := a; min := b;
        end
        else
        begin
            max := b; min := a;
        end;
        inc(s, min);
        for j := 0 to 3 do
        begin
            k := (j - (max - min)) mod 4;
            if k < 0 then
                inc(k, 4);
            if min1[k] + max - min < min1[j] then
                min2[j] := min1[k] + max - min
            else
                min2[j] := min1[j];
        end;
        for j := 0 to 3 do
            min1[j] := min2[j];
    end;
    if s mod 4 > 0 then
    begin
        k := 4 - (s mod 4);
        if min1[k] = 100001 then
            s := 0
        else
            inc(s, min1[k]);
    end;
    writeln(s);
end.