type llist = ^element;
    element = record
                e, k: integer;
                next: llist;
              end;

var input, output: text;
    p, q: llist;
    n, e, k, i, count: longint;

procedure add(e, k: longint; var list: llist);
var temp: llist;
Begin
    new(temp);
    temp^.next := list;
    temp^.e := e;
    temp^.k := k;
    list := temp;
end;

procedure writeList(list: llist);
Begin
    while list <> nil do
        Begin
        if list^.k <> 0 then Begin write(output, list^.e, ' ', list^.k); writeln(output); end;
        list := list^.next;
        end;
end;

procedure searchAdd(var p, q: llist);
var tempP, tempQ, destr: llist;
Begin
    tempP := p;
    while tempP <> nil do
        Begin
        tempQ := q;
        while tempQ <> nil do
            Begin
            if tempP^.e = tempQ^.e then
                Begin
                tempP^.k := tempP^.k + tempQ^.k;
                destr := tempQ^.next;
                if (tempQ = q) and (q^.next = nil) then
                    Begin
                    destr := q;
                    q := nil;
                    dispose(destr);
                    end
                else if destr <> nil then
                    Begin
                    tempQ^.e := tempQ^.next^.e;
                    tempQ^.k := tempQ^.next^.k;
                    tempQ^.next := tempQ^.next^.next;
                    dispose(destr);
                    end
                else if destr = nil then
                    Begin
                    tempQ := q;
                    while tempQ^.next^.next <> nil do
                        tempQ := tempQ^.next;
                    destr := tempQ^.next;
                    tempQ^.next := nil;
                    dispose(destr);
                    end;
                break;
                end;
            tempQ := tempQ^.next;
            end;
        tempP := tempP^.next;
        end;
    tempP := p;
    if q <> nil then
        Begin
        while tempP^.next <> nil do
            tempP := tempP^.next;
        tempP^.next := q;
        end;
end;

procedure sortList(var list: llist);
var  temp: llist;
    change : boolean;
    numTemp : longint;
Begin
    count := 0;
    repeat
        temp := list;
        change := False;
        while temp^.next <> nil do
            Begin
            if temp^.e < temp^.next^.e then
                Begin
                numTemp := temp^.e;
                temp^.e := temp^.next^.e;
                temp^.next^.e := numTemp;
                numTemp := temp^.k;
                temp^.k := temp^.next^.k;
                temp^.next^.k := numTemp;
                change := True;
                end;
            temp := temp^.next;
            end;
    until not change;
    temp := p;
    while temp <> nil do
        Begin
        if temp^.k <> 0 then count := count + 1;
        temp := temp^.next;
        end;
    writeln(output, count);
end;

Begin
    assign(input, 'polynomy.in'); reset(input);
    assign(output, 'polynomy.out'); rewrite(output);
    p := nil;
    q := nil;
    readln(input, n);
    for i := 1 to n do
        Begin
        read(input, e);
        readln(input, k);
        add(e, k, p);
        end;
    readln(input, n);
    for i := 1 to n do
        Begin
        read(input, e);
        readln(input, k);
        add(e, k, q);
        end;
    searchAdd(p, q);
    sortList(p);
    writeList(p);
    close(input); close(output);
end.