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 "iostream"
# include "cstdio"

using namespace std;

const int maxm=1e5+10;

int N,A[maxm];

int main(){
	register int i,Ans=0;
	scanf("%d",&N);
	for(i=1;i<=N;i++) scanf("%d",A+i);
	for(i=1;i<=N;i++){
		if(A[i]<A[i-1]) continue;
		Ans+=(A[i]-A[i-1]);
	}
	printf("%d",Ans);
	return 0;
}