Problem:
Score : 1000 points

Problem Statement

You are given a sequence a = \{a_1, ..., a_N\} with all zeros, and a sequence b = \{b_1, ..., b_N\} consisting of 0 and 1. The length of both is N.

You can perform Q kinds of operations. The i-th operation is as follows:

Replace each of a_{l_i}, a_{l_i + 1}, ..., a_{r_i} with 1.

Minimize the hamming distance between a and b, that is, the number of i such that a_i \neq b_i, by performing some of the Q operations.

Constraints

1 \leq N \leq 200,000

b consists of 0 and 1.

1 \leq Q \leq 200,000

1 \leq l_i \leq r_i \leq N

If i \neq j, either l_i \neq l_j or r_i \neq r_j.

Input

Input is given from Standard Input in the following format:

N
b_1 b_2 ... b_N
Q
l_1 r_1
l_2 r_2
:
l_Q r_Q

Output

Print the minimum possible hamming distance.

Sample Input 1

3
1 0 1
1
1 3

Sample Output 1

1

If you choose to perform the operation, a will become \{1, 1, 1\}, for a hamming distance of 1.

Sample Input 2

3
1 0 1
2
1 1
3 3

Sample Output 2

0

If both operations are performed, a will become \{1, 0, 1\}, for a hamming distance of 0.

Sample Input 3

3
1 0 1
2
1 1
2 3

Sample Output 3

1

Sample Input 4

5
0 1 0 1 0
1
1 5

Sample Output 4

2

It may be optimal to perform no operation.

Sample Input 5

9
0 1 0 1 1 1 0 1 0
3
1 4
5 8
6 7

Sample Output 5

3

Sample Input 6

15
1 1 0 0 0 0 0 0 1 0 1 1 1 0 0
9
4 10
13 14
1 7
4 14
9 11
2 6
7 8
3 12
7 13

Sample Output 6

5

Sample Input 7

10
0 0 0 1 0 0 1 1 1 0
7
1 4
2 5
1 3
6 7
9 9
1 5
7 9

Sample Output 7

1

Solution in Rust (1.42.0) (judge verdict: Runtime Error)

use proconio::{input, marker::Usize1};
// ordtools {{{
#[allow(dead_code)]
mod ordtools {
    pub trait Ordtools: PartialOrd + Clone + Sized {
        fn change_min(&mut self, rhs: Self) {
            if &rhs < self {
                *self = rhs.clone();
            }
        }

        fn change_max(&mut self, mut rhs: Self) {
            if self < &mut rhs {
                *self = rhs.clone();
            }
        }
    }

    impl<T: PartialOrd + Clone + Sized> Ordtools for T {}
}
// }}}
use ordtools::Ordtools;

fn main() {
    input!(n: usize, b: [u32; n], q: usize, mut lr: [(Usize1, usize); q]);
    lr.sort();

    let mut cost = vec![vec![0; n + 1]; n + 1];
    (0..n).for_each(|i| cost[i][i + 1] = if b[i] == 0 { 1 } else { -1 });
    for i in 0..n {
        for j in i + 2..=n {
            cost[i][j] = cost[i][j - 1] + cost[j - 1][j];
        }
    }

    let mut dp = vec![std::i32::MAX; n + 1];
    dp[0] = b.iter().sum::<u32>() as i32;
    let mut pos = 0;
    for &(l, r) in &lr {
        while pos < l {
            let x = dp[pos];
            dp[pos + 1].change_min(x);
            pos += 1;
        }
        for j in l..r {
            let x = dp[j];
            dp[r].change_min(x.saturating_add(cost[j][r]));
        }
    }
    println!("{}", dp.iter().min().unwrap());
}