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
#include <bits/stdc++.h>
using namespace std;
 
int main(){
  int n; cin >> n;
  vector<int> h(n);  for(auto &x : h) cin >> x;
  int ans = h[0];
 
  // 結局単調増加な山を登るだけ
  for (int i = 1; i < n; i++) {
    if(h[i] - h[i-1] > 0) ans += h[i] - h[i-1];
  }
 
  std::cout << ans << '\n';
}