import java.util.*;
public class Main {
	
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int N = sc.nextInt();
        int[] map = new int[N+1];
        for (int i = 0; i < N; i++) {
        	map[i] = sc.nextInt();
        }
        
        map[N] = 0;
        
        int ans = 0;
        int now = map[0];
        for (int i = 1; i < N+1; i++) {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        }
        
        System.out.println(ans);
    }
} 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[] map = new int[N+1];
        for (int i = 0; i < N; i++) {
        	map[i] = sc.nextInt();
        }
        
        map[N] = 0;
        
        int ans = 0;
        int now = map[0];
        for (int i = 1; i < N+1; i++) {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        }
        
        System.out.println(ans);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int N = sc.nextInt();
        int[] map = new int[N+1];
        for (int i = 0; i < N; i++) {
        	map[i] = sc.nextInt();
        }
        
        map[N] = 0;
        
        int ans = 0;
        int now = map[0];
        for (int i = 1; i < N+1; i++) {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        }
        
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        
        int N = sc.nextInt();
        int[] map = new int[N+1];
        for (int i = 0; i < N; i++) {
        	map[i] = sc.nextInt();
        }
        
        map[N] = 0;
        
        int ans = 0;
        int now = map[0];
        for (int i = 1; i < N+1; i++) {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        }
        
        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[] map = new int[N+1]; map new int[N+1] N+1 N 1 for (int i = 0; i < N; i++) {
        	map[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
        	map[i] = sc.nextInt();
        } {
        	map[i] = sc.nextInt();
        } map[i] = sc.nextInt() map[i] map i sc.nextInt() sc.nextInt sc map[N] = 0 map[N] map N 0 int ans = 0; ans 0 int now = map[0]; now map[0] map 0 for (int i = 1; i < N+1; i++) {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        } int i = 1; int i = 1; i 1 i < N+1 i N+1 N 1 i++ i++ i {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        } {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        } if (now > map[i]) {
        		ans += now - map[i];
        	} now > map[i] now map[i] map i {
        		ans += now - map[i];
        	} ans += now - map[i] ans now - map[i] now map[i] map i now = map[i] now map[i] map i 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[] map = new int[N+1];
        for (int i = 0; i < N; i++) {
        	map[i] = sc.nextInt();
        }
        
        map[N] = 0;
        
        int ans = 0;
        int now = map[0];
        for (int i = 1; i < N+1; i++) {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        }
        
        System.out.println(ans);
    }
} public class Main {
	
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int N = sc.nextInt();
        int[] map = new int[N+1];
        for (int i = 0; i < N; i++) {
        	map[i] = sc.nextInt();
        }
        
        map[N] = 0;
        
        int ans = 0;
        int now = map[0];
        for (int i = 1; i < N+1; i++) {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        }
        
        System.out.println(ans);
    }
} Main
import java.util.*;
public class Main {
	
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int N = sc.nextInt();
        int[] map = new int[N+1];
        for (int i = 0; i < N; i++) {
        	map[i] = sc.nextInt();
        }
        
        map[N] = 0;
        
        int ans = 0;
        int now = map[0];
        for (int i = 1; i < N+1; i++) {
        	if (now > map[i]) {
        		ans += now - map[i];
        	}
        	now = map[i];
        }
        
        System.out.println(ans);
    }
}