import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt(); in.nextLine();
        String[] tmp = in.nextLine().split(" ");
        int[] ary = new int[n+1];
        for( int i = 1; i <= n; i++ ) ary[i] = Integer.parseInt(tmp[i-1]);
        int ans = 0;
        for( int i = 1; i < n+1; i++ ) {
            if( ary[i]-ary[i-1]>0 ) ans += ary[i]-ary[i-1];
        }
        System.out.println(ans);
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz