There are two kinds of pearls: black and white. When a black pearl is the left of a white pearl and they are adjacent to each other, then they will disappear. 
Now, there are n strings of pearls, each string with \(a_i\) white pearls on the left and \(b_i\) black pearls on the right. Calculate the minimum number of the rest pearls when connecting these n strings.

The first line contains an integer \(T\), indicating the number of test cases. For each test case:
The first line contains an integer \(n(1\le n\le 100\ 000)\), indicating the number of the string of beads.
Each of the next (n) lines contains two integers \(a_i, b_i(a_i \ge 0, b_i \ge 0, 1\le a_i+b_i\le10\ 000)\).
It is guaranteed that \(\sum (a_i+b_i)\le500\ 000\).

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