import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        PrintWriter out = new PrintWriter(System.out);
        InputStreamScanner in = new InputStreamScanner(System.in);
        new Main().solve(in, out);
        out.flush();
    }

    private void solve(InputStreamScanner in, PrintWriter out) {
        int n = in.nextInt();

        int[] h = new int[n];
        for (int i = 0; i < n; i++) {
            h[i] = in.nextInt();
        }

        int[] g = new int[n];
        out.println(calc(h, g));
    }

    private int calc(int[] h, int[] g) {
        int r = 0;

        boolean all = true;

        int prev = -1;
        while (all) {
            int m = 100;
            for (int i = 0; i < h.length; i++) {
                if (h[i] == g[i]) {
                    if (i - prev > 1) {
                        r += calc(Arrays.copyOfRange(h, prev + 1, i), Arrays.copyOfRange(g, prev + 1, i));
                    }
                    prev = i;
                    all = false;
                } else {
                    m = Math.min(m, h[i] - g[i]);
                }
            }

            if (all) {
                for (int i = 0; i < h.length; i++) {
                    g[i] += m;
                }
                r += m;
            } else {
                if (prev + 1 != h.length) {
                    r += calc(Arrays.copyOfRange(h, prev + 1, h.length), Arrays.copyOfRange(g, prev + 1, h.length));
                }
            }
        }

        return r;
    }

    static class InputStreamScanner {

        private InputStream in;

        private byte[] buf = new byte[1024];
        private int len = 0;
        private int off = 0;

        InputStreamScanner(InputStream in)	{
            this.in = in;
        }

        String next() {
            StringBuilder sb = new StringBuilder();
            for (int b = skip(); !isSpace(b);){
                sb.appendCodePoint(b);
                b = read();
            }
            return sb.toString();
        }

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

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        char nextChar() {
            return (char)skip();
        }

        int skip() {
            for (int b; (b = read()) != -1;) {
                if (!isSpace(b)) {
                    return b;
                }
            }
            return -1;
        }

        private boolean isSpace(int c) {
            return c < 33 || c > 126;
        }

        private int read() {
            if (len == -1) {
                throw new InputMismatchException("End of Input");
            }
            if (off >= len){
                off = 0;
                try {
                    len = in.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException(e.getMessage());
                }
                if (len <= 0) {
                    return -1;
                }
            }
            return buf[off++];
        }
    }
}


Measured memory_bytes: 21204