import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author anand.oza
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CGrandGarden solver = new CGrandGarden();
        solver.solve(1, in, out);
        out.close();
    }

    static class CGrandGarden {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[] h = new int[n];
            for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            }
            int max = Integer.MIN_VALUE;
            for (int x : h)
                max = Math.max(max, x);

            int answer = 0;
            for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            }

            out.println(answer);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.StringTokenizer; StringTokenizer java.util import java.io.IOException; IOException java.io import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.InputStream; InputStream java.io public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CGrandGarden solver = new CGrandGarden();
        solver.solve(1, in, out);
        out.close();
    }

    static class CGrandGarden {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[] h = new int[n];
            for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            }
            int max = Integer.MIN_VALUE;
            for (int x : h)
                max = Math.max(max, x);

            int answer = 0;
            for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            }

            out.println(answer);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CGrandGarden solver = new CGrandGarden();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CGrandGarden solver = new CGrandGarden();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out InputReader in = new InputReader(inputStream); in new InputReader(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) CGrandGarden solver = new CGrandGarden(); solver new CGrandGarden() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class CGrandGarden {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[] h = new int[n];
            for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            }
            int max = Integer.MIN_VALUE;
            for (int x : h)
                max = Math.max(max, x);

            int answer = 0;
            for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            }

            out.println(answer);
        }

    } CGrandGarden public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[] h = new int[n];
            for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            }
            int max = Integer.MIN_VALUE;
            for (int x : h)
                max = Math.max(max, x);

            int answer = 0;
            for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            }

            out.println(answer);
        } solve {
            int n = in.nextInt();
            int[] h = new int[n];
            for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            }
            int max = Integer.MIN_VALUE;
            for (int x : h)
                max = Math.max(max, x);

            int answer = 0;
            for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            }

            out.println(answer);
        } int n = in.nextInt(); n in.nextInt() in.nextInt in int[] h = new int[n]; h new int[n] n for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                h[i] = in.nextInt();
            } {
                h[i] = in.nextInt();
            } h[i] = in.nextInt() h[i] h i in.nextInt() in.nextInt in int max = Integer.MIN_VALUE; max Integer.MIN_VALUE Integer Integer.MIN_VALUE for (int x : h)
                max = Math.max(max, x); int x h max = Math.max(max, x); max = Math.max(max, x) max Math.max(max, x) Math.max Math max x int answer = 0; answer 0 for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            } int i = max; int i = max; i max i > 0 i 0 i-- i-- i {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            } {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            } int tot = 0 tot 0 pairs = 0; pairs 0 for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                } {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                } if (h[j] >= i)
                        tot++; h[j] >= i h[j] h j i tot++ tot if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++; h[j] >= i && j + 1 < n && h[j + 1] >= i h[j] >= i && j + 1 < n && h[j + 1] >= i h[j] >= i h[j] h j i j + 1 < n j + 1 j 1 n h[j + 1] >= i h[j + 1] h j + 1 j 1 i pairs++ pairs answer += (tot - pairs) answer (tot - pairs) tot pairs out.println(answer) out.println out answer int testNumber testNumber InputReader in in PrintWriter out out static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    } InputReader public BufferedReader reader; reader public StringTokenizer tokenizer; tokenizer public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } InputReader {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } reader = new BufferedReader(new InputStreamReader(stream), 32768) reader new BufferedReader(new InputStreamReader(stream), 32768) tokenizer = null tokenizer null InputStream stream stream public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } next {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    tokenizer = new StringTokenizer(reader.readLine());
                } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CGrandGarden solver = new CGrandGarden();
        solver.solve(1, in, out);
        out.close();
    }

    static class CGrandGarden {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[] h = new int[n];
            for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            }
            int max = Integer.MIN_VALUE;
            for (int x : h)
                max = Math.max(max, x);

            int answer = 0;
            for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            }

            out.println(answer);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CGrandGarden solver = new CGrandGarden();
        solver.solve(1, in, out);
        out.close();
    }

    static class CGrandGarden {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[] h = new int[n];
            for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            }
            int max = Integer.MIN_VALUE;
            for (int x : h)
                max = Math.max(max, x);

            int answer = 0;
            for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            }

            out.println(answer);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author anand.oza
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CGrandGarden solver = new CGrandGarden();
        solver.solve(1, in, out);
        out.close();
    }

    static class CGrandGarden {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int[] h = new int[n];
            for (int i = 0; i < n; i++) {
                h[i] = in.nextInt();
            }
            int max = Integer.MIN_VALUE;
            for (int x : h)
                max = Math.max(max, x);

            int answer = 0;
            for (int i = max; i > 0; i--) {
                int tot = 0, pairs = 0;
                for (int j = 0; j < n; j++) {
                    if (h[j] >= i)
                        tot++;
                    if (h[j] >= i && j + 1 < n && h[j + 1] >= i)
                        pairs++;
                }
                answer += (tot - pairs);
            }

            out.println(answer);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}

