题号：NC50902
时间限制：C/C++/Rust/Pascal 2秒，其他语言4秒
空间限制：C/C++/Rust/Pascal 256 M，其他语言512 M
64bit IO Format: %lld
时间限制：C/C++/Rust/Pascal 2秒，其他语言4秒
空间限制：C/C++/Rust/Pascal 256 M，其他语言512 M
64bit IO Format: %lld
题目描述
Given an array A of length 
containing only 1 and -1. The number of 1 is not more than 
.
Please count how many pairs of (l, r) satisfy
and 
.
Please count how many pairs of (l, r) satisfy
输入描述:
The first line of input contains an integers N indicating how many segments of A is 1.
Following N lines each contains two space-separated integersindicating that
is 1 for
for
输出描述:
Output one line containing an integer representing the answer.