#define int long long
using namespace std;
const int N=1e5+5;
int n;
int a[N];
int diff[N];
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	cin>>n;
	int sum=0;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		diff[i]=a[i]-a[i-1];
		if(diff[i]>0) sum+=diff[i];
	}
	cout<<sum<<"\n";
	return 0;
}