Trapezoid Sum

AtCoder

IDabc181_b

Time2000ms

Memory256MB

Difficulty—

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: $N$ $A_1$ $B_1$ $\vdots$ $A_N$ $B_N$ [samples]

Samples

Input #1

2
1 3
3 5

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 $1+2+3+3+4+5=18$.

Input #2

Output #2

998244353

Input #3

1
1 1000000

Output #3

500000500000

API Response (JSON)

{
  "problem": {
    "name": "Trapezoid Sum",
    "description": {
      "content": "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 tot",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc181_b"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "We have a blackboard with nothing written on it. Takahashi will do $N$ operations to write integers on it.\nIn the $i$\\-th operation, he will write each integer from $A_i$ through $B_i$ once, for a tot...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

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