#include <iostream>
using namespace std;
const int N = 100010;
int a[N];
int n;
int res = 0;
int main()
{
cin >> n;
for(int i = 0; i < n; i++)
cin >> a[i];
int last = 0;
for(int i = 0; i < n; i++)
{
if(a[i] > last) res += a[i] - last;
last = a[i];
}
cout << res;
return 0;
}