#include <bits/stdc++.h>

using namespace std;

const int N = 32768;
const int INF = 0x3f3f3f3f;
int a[N];
int n;
//10个测试点过了3个，得30分，7个测试点TLE
int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    int sum = a[1];
    for (int i = 2; i <= n; i++) {
        //每一个都向前找，找出差的绝对值最小的数
        int minX = INF;
        for (int j = i - 1; j >= 1; j--)
            if (abs(a[j] - a[i]) < minX) minX = abs(a[j] - a[i]);
        sum += minX;
    }
    cout << sum << endl;
    return 0;
}