import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int prev = 0;
		long count = 0;
		for (int i = 1; i <= n; i++) {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		}
		System.out.println(count);
   }
} import java.util.*; util.* java public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int prev = 0;
		long count = 0;
		for (int i = 1; i <= n; i++) {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		}
		System.out.println(count);
   }
} Main public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int prev = 0;
		long count = 0;
		for (int i = 1; i <= n; i++) {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		}
		System.out.println(count);
   } main {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int prev = 0;
		long count = 0;
		for (int i = 1; i <= n; i++) {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		}
		System.out.println(count);
   } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int prev = 0; prev 0 long count = 0; count 0 for (int i = 1; i <= n; i++) {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		} int i = 1; int i = 1; i 1 i <= n i n i++ i++ i {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		} {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		} int x = sc.nextInt(); x sc.nextInt() sc.nextInt sc count += Math.max(x - prev, 0) count Math.max(x - prev, 0) Math.max Math x - prev x prev 0 prev = x prev x System.out.println(count) System.out.println System.out System System.out count String[] args args public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int prev = 0;
		long count = 0;
		for (int i = 1; i <= n; i++) {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		}
		System.out.println(count);
   }
} public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int prev = 0;
		long count = 0;
		for (int i = 1; i <= n; i++) {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		}
		System.out.println(count);
   }
} Main
import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int prev = 0;
		long count = 0;
		for (int i = 1; i <= n; i++) {
		    int x = sc.nextInt();
		    count += Math.max(x - prev, 0);
		    prev = x;
		}
		System.out.println(count);
   }
}
