#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <limits.h>

typedef struct _Node {
    int height;
    struct _Node* l, *r;
}Node;

Node* createNode (int h) {
    Node* newNode = (Node*) malloc (sizeof(Node));
    newNode->height = h;
    newNode->l = NULL;
    newNode->r = NULL;
}

Node* constructTree (int* arr, int N, int index) {
    if (index >= N)
        return NULL;

    Node* newNode = createNode(arr[index]);
    if (newNode == NULL)
        return NULL;

    newNode->l = constructTree(arr, N, index + 1);
    newNode->r = constructTree(arr, N, index + 2);

    return newNode;
}

void dfs (Node* root, int* min, int pre) {
    if (root == NULL) return;
    if (root->l == NULL && root->r == NULL) {
        if (pre < *min)
            *min = pre;
    }
    if (root->l != NULL)
        dfs (root->l, min, pre + abs(root->height - root->l->height));
    if (root->r != NULL)
        dfs (root->r, min, pre + abs(root->height - root->r->height));

    return;
}

int main() {
    int N;
    scanf("%d", &N);

    int arr[N];
    for (int i = 0; i < N; i++)
        scanf("%d", &arr[i]);

    Node* root = constructTree (arr, N, 0);

    int value = INT_MAX;
    int *min = &value;
    int prefix = 0;

    dfs (root, min, prefix);
    printf("%d\n", *min);

    return 0;
}