2023FEB a big problem
Bessie is a hungry cow. Each day, for dinner, if there is a haybale in the barn, she will eat one haybale. Farmer John does not want Bessie to starve, so some days he sends a delivery of haybales, which arrive in the morning (before dinner). In particular, on day
, Farmer John sends a delivery of
haybales (
,
).
Compute the total number of haybales Bessie will eat during the first
days.
INPUT FORMAT (input arrives from the terminal / stdin):
The first line contains
and
(
,
).
The next
lines each contain
and
. It is additionally guaranteed that
.
OUTPUT FORMAT (print output to the terminal / stdout):
Output the number of haybales that Bessie will eat during the first
days.
Note that the large size of integers involved in this problem may require the use of 64-bit integer data types (e.g., a "long long" in C/C++).
SAMPLE INPUT:
1 5
1 2
SAMPLE OUTPUT:
2
Two haybales arrive on the morning of day
. Bessie eats one haybale for dinner on day
and another haybale on day
. On days
, there are no more haybales for Bessie to eat. In total, Bessie eats
haybales during the first
days.
SAMPLE INPUT:
2 5
1 2
5 10
SAMPLE OUTPUT:
3
Two haybales arrive on the morning of day
. Bessie eats one haybale on days
and
. There are no haybales for Bessie to eat on days
and
. On the morning of day
,
haybales arrive. Bessie eats one haybale for dinner on day
. In total, Bessie eats
haybales during the first
days.
SAMPLE INPUT:
2 5
1 10
5 10
SAMPLE OUTPUT:
5
haybales arrive on the morning of day
. Bessie eats one haybale on days
. On the morning of day
, another
haybales arrive, meaning there are
haybales in the barn. For dinner on day
, Bessie eats another haybale. In total, Bessie eats
haybales during the first
days.
SCORING:
Inputs 4-7:
Inputs 8-13: No additional constraints.
English:
```c++
贝茜是一头饥饿的母牛。每天，晚餐时，如果谷仓里有干草， 草包。农夫约翰不想让贝茜挨饿，所以有些 天他寄来一批干草包，早上到达（之前 晚餐）。特别是在当天
，农夫约翰发送了送货
干草包（
,
).
计算贝茜在第一次吃的干草包总数
日。
输入格式（输入从终端/标准到达）：
第一行包含
和
(
,
).
下一个
每行包含
和
.这是额外的保证 那
.
输出格式（打印输出到终端/标准输出）：
输出贝西在第一次吃的干草包数量
日。
请注意，此问题中涉及的大整数可能需要 使用 64 位整数数据类型（例如，C/C++ 中的“long long”）。
示例输入：
1 5
1 2
示例输出：
2
两个干草包在一天早上到达
.贝茜吃一个干草包 当天晚餐
当天还有另一个干草包
.在几天
那里 不再有干草包给贝茜吃。总的来说，贝西吃
干草包 在第一次
日。
示例输入：
2 5
1 2
5 10
示例输出：
3
两个干草包在一天早上到达
.贝茜每天吃一个干草包
和
.贝茜天没有干草包吃
和
.在 一天中的早晨
,
干草包到了。贝茜晚餐吃一根干草包 日
.总的来说，贝西吃
第一次干草包
日。
示例输入：
2 5
1 10
5 10
示例输出：
5
干草包在一天早上到达
.贝茜每天吃一个干草包
.在一天的早晨
另一个
干草包到来，意思是 有
谷仓里的干草包。当天晚餐
，贝茜又吃了一遍 海贝尔。总的来说，贝西吃
第一次干草包
日。
得分：
输入 4-7：
输入 8-13：无其他约束。
截图：
