Problem:
Score : 300 points

Problem Statement

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.

Sample Input 1

4
1 2 2 1

Sample Output 1

2

The minimum number of watering operations required is 2.
One way to achieve it is:

Perform the operation with (l,r)=(1,3).

Perform the operation with (l,r)=(2,4).

Sample Input 2

5
3 1 2 3 1

Sample Output 2

5

Sample Input 3

8
4 23 75 0 23 96 50 100

Sample Output 3

221

Solution in JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

process.stdin.resume();
process.stdin.setEncoding('utf8');
var input_string = '';

process.stdin.on('data', function(chunk) {
    input_string += chunk;
});

process.stdin.on('end', function() {
  const lines = input_string.split("\n");
  const n = parseInt(lines[0]);
  const ks = lines[1].split(" ");
  const k = [];
  for(var i=0; i<n; i++){
    k[i] = parseInt(ks[i]);
    }
  var t = 0;
  var changed = true;
  while(changed){
    changed = false;
    for(var i=0;i<n;i++){
      if(k[i]>0){
      for(var j=i+1;j<n&&k[i]<=k[j];j++){
        k[j]--;
      }
      k[i]--;
      t++;
        changed = true;
      }
    }
  }
  console.log(t);
});