import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] h = new int[n];
        for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }
        int ans = 0;
        while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        }
        System.out.println(ans);
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] h = new int[n];
        for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }
        int ans = 0;
        while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        }
        System.out.println(ans);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] h = new int[n];
        for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }
        int ans = 0;
        while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        }
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] h = new int[n];
        for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }
        int ans = 0;
        while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        }
        System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] h = new int[n]; h new int[n] n for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i < h.length i h.length h h.length i++ i++ i {
            h[i] = sc.nextInt();
        } {
            h[i] = sc.nextInt();
        } h[i] = sc.nextInt() h[i] h i sc.nextInt() sc.nextInt sc int ans = 0; ans 0 while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        } true {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        } boolean flg = false; flg false for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            } {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            } if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                } h[i] != 0 h[i] h i 0 {
                    h[i]--;
                    flg = true;
                } h[i]-- h[i] h i flg = true flg true if(flg){
                    break;
                } flg {
                    break;
                } break; if(!flg) {
                break;
            } !flg flg {
                break;
            } break; ans++ ans System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] h = new int[n];
        for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }
        int ans = 0;
        while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        }
        System.out.println(ans);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] h = new int[n];
        for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }
        int ans = 0;
        while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        }
        System.out.println(ans);
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] h = new int[n];
        for (int i = 0; i < h.length; i++) {
            h[i] = sc.nextInt();
        }
        int ans = 0;
        while(true) {
            boolean flg = false;
            for (int i = 0; i < n; i++) {
                if(h[i] != 0) {
                    h[i]--;
                    flg = true;
                } else if(flg){
                    break;
                }
            }
            if(!flg) {
                break;
            }
            ans++;
        }
        System.out.println(ans);
    }
}