Grand Garden

In a flower bed, there are N flowers, numbered 1,2,......,N. Initially, the heights of all flowers are 0. You are given a sequence h=\{h_1,h_2,h_3,......\} as input. You would like to change the height of Flower k to h_k for all k (1 \leq k \leq N), by repeating the following "watering" operation:

• Specify integers l and r. Increase the height of Flower x by 1 for all x such that l \leq x \leq r.

Find the minimum number of watering operations required to satisfy the condition.

Constraints

• 1 \leq N \leq 100
• 0 \leq h_i \leq 100
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

N h_1 h_2 h_3 ...... h_N

Output

Print the minimum number of watering operations required to satisfy the condition.

Examples

Input

4 1 2 2 1

Output

2

Input

5 3 1 2 3 1

Output

5

Input

8 4 23 75 0 23 96 50 100

Output

221

inputFormat

input. You would like to change the height of Flower k to h_k for all k (1 \leq k \leq N), by repeating the following "watering" operation:

• Specify integers l and r. Increase the height of Flower x by 1 for all x such that l \leq x \leq r.

Find the minimum number of watering operations required to satisfy the condition.

Constraints

• 1 \leq N \leq 100
• 0 \leq h_i \leq 100
• All values in input are integers.

Input

Input is given from Standard Input in the following format:

N h_1 h_2 h_3 ...... h_N

outputFormat

Output

Print the minimum number of watering operations required to satisfy the condition.

Examples

Input

4 1 2 2 1

Output

2

Input

5 3 1 2 3 1

Output

5

Input

8 4 23 75 0 23 96 50 100

Output

221

样例

4
1 2 2 1

2