With your help, the army list attacked Huang Bo’s castle several times, however, Huang Bo always win these wars. Then, the army master wants to know the combat values of among different soldiers.

As you may know, it has different solider
levels in this plant, e.g., level 1 is (x), level 2 is (x^2), …, level n is
(x^n). The combat value of soldiers in each branch can be represented by** polynomial with level char x**. For
example, one soldier branch is f(x) = x+x^2+2x^3, the other solider branch is g(x)
= x^2. The total combat values of soldiers in this planet is defined as addition
among two polynomials. In above example, the total combat values of soldiers
are h(x)= x+2x^2+2x^3. **ItakEjgo** asks
you for help as he is not good at math. Each time, **ItakEjgo** will give you the (**coefficient,
exponent) **pairs (i.e., in ascending order of soldiers level) of two
polynomials. For example, f(x) = 1+2x+3x^2 will be given as (1 0), (2 1), (3 2).
You return the **polynomial after addition
to him**. Since the soldiers may be injured in the war, so the coefficients could
be negative values.

Note that, to help army master to understand:

**Please pay attention to the special cases, e.g., the result is 0, the sum of compact values is 0 or 1 at level i. We follow all these definitions and notations in Math.
**