Maximize Ticket Distribution

You are given N ticket categories. For each category, there are two numbers: the number of tickets available and the number of prizes available. A category can distribute at most \(\min(\text{tickets}, \text{prizes})\) tickets. Your task is to compute the maximum number of tickets that can be distributed across all categories.

Note: The value \(\min(a, b)\) represents the minimum of \(a\) and \(b\).

inputFormat

The input is read from stdin and has the following format:

1. The first line contains a single integer \(N\) which represents the number of ticket categories.
2. Each of the following \(N\) lines contains two space-separated integers. The first integer represents the number of tickets available for the category, and the second integer represents the number of prizes available.

outputFormat

Output a single integer to stdout, which is the maximum number of tickets that can be distributed across all categories.

3
10 2
15 3
20 5

10