Overall Financial Outcome

You are given a list of workshops. Each workshop is described by two integers (a) and (b), where (a) is the registration fee and (b) is the cost to organize the workshop. Your task is to compute the overall financial outcome, which is defined as the sum of (a - b) for each workshop. The final result should be rounded to two decimal places. Note that the outcome can be negative.

inputFormat

The first line contains a single integer (N) representing the number of workshops. The following (N) lines each contain two space-separated integers (a) and (b) representing the registration fee and the cost to organize the workshop, respectively.

outputFormat

Output a single number which is the overall financial outcome rounded to two decimal places.## sample

3
100 200
150 180
120 120

-130.00