Score : 200 points
Joisino is working as a receptionist at a theater.
The theater has 100000 seats, numbered from 1 to 100000.
According to her memo, N groups of audiences have come so far, and the i-th group occupies the consecutive seats from Seat l_i to Seat r_i (inclusive).
How many people are sitting at the theater now?
Input is given from Standard Input in the following format:
N l_1 r_1 : l_N r_N
Print the number of people sitting at the theater.
1 24 30
7
There are 7 people, sitting at Seat 24,25,26,27,28,29 and 30.
2 6 8 3 3
4