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,sum=0;
  cin>>n;
  vector<int> u(n),v(n);
  for(int i=0;i<n;++i)cin>>u[i];
  v[0]=u[0];
  for(int i=1;i<n;++i)v[i]=u[i]-u[i-1];
  for(int i=0;i<n;++i)if(v[i]>0)sum+=v[i];
  cout<<sum;
  return 0;
}