Contest: Task: Related: TaskA TaskC

Score : $200$ points

We have a blackboard with nothing written on it. Takahashi will do $N$ operations to write integers on it.

In the $i$-th operation, he will write each integer from $A_i$ through $B_i$ once, for a total of $B_i - A_i + 1$ integers.

Find the sum of the integers written on the blackboard after the $N$ operations.

- All values in input are integers.
- $1 \leq N \leq 10^5$
- $1 \leq A_i \leq B_i \leq 10^6$

Input is given from Standard Input in the following format:

$N$ $A_1$ $B_1$ $\vdots$ $A_N$ $B_N$

Print the sum of the integers written on the blackboard after the $N$ operations.

2 1 3 3 5

18

In the $1$-st operation, he will write $1$, $2$, and $3$ on the blackboard.

In the $2$-nd operation, he will write $3$, $4$, and $5$ on the blackboard.

The sum of the integers written is $1+2+3+3+4+5=18$.

3 11 13 17 47 359 44683

998244353

1 1 1000000

500000500000