The creators of a new
programming language D++ have found out that whatever limit for SuperLongInt
type they make, sometimes programmers need to operate even larger numbers. A limit
of 1000 digits is so small... You have to find the sum of two numbers with
maximal size of 1.000.000 digits.

The first line of a input file is an integer N, then a
blank line followed by N input blocks. The
first line of an each input block contains a single number M (1<=M<=1000000)
— the length of the integers (in order to make their lengths equal, some
leading zeroes can be added). It is followed by these integers written in
columns. That is, the next M lines contain two digits each, divided by a space.
Each of the two given integers is not less than 1, and the length of their sum
does not exceed M.

There is a blank line between input blocks.

## The Output

Each output block should contain exactly M digits in a
single line representing the sum of these two integers.

There is a blank line between output blocks.

## Sample Input

2
4
0 4
4 2
6 8
3 7
3
3 0
7 9
2 8

4750
470