#include<iostream>
#include<algorithm>
using namespace std;
int a[100005]={0},f[100005]={0};
int main()
{
    int m(0),n;
    cin>>n;
    for (int i=1;i<=n;i++) cin>>a[i];
    for (int i=1;i<=n;i++)
        if (a[i]>a[i-1]) m+=a[i]-a[i-1];
    cout<<m<<endl;
    return 0;
}
    

/**************************************************************
	Problem: 2327
	User: admin
	Language: C++
	Result: Accepted
	Time:74 ms
	Memory:2856 kb
****************************************************************/