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Contest: Task: Related: TaskC TaskE

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