101811: [AtCoder]ABC181 B - Trapezoid Sum
Memory Limit:256 MB
Time Limit:2 S
Judge Style:Text Compare
Creator:
Submit:0
Solved:0
Description
Score : $200$ points
Problem Statement
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.
Constraints
- All values in input are integers.
- $1 \leq N \leq 10^5$
- $1 \leq A_i \leq B_i \leq 10^6$
Input
Input is given from Standard Input in the following format:
$N$ $A_1$ $B_1$ $\vdots$ $A_N$ $B_N$
Output
Print the sum of the integers written on the blackboard after the $N$ operations.
Sample Input 1
2 1 3 3 5
Sample Output 1
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 $1+2+3+3+4+5=18$.
Sample Input 2
3 11 13 17 47 359 44683
Sample Output 2
998244353
Sample Input 3
1 1 1000000
Sample Output 3
500000500000