import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.NoSuchElementException;

public class Main {

	public static void main(String[] args) {
		FScanner sc = new FScanner();
		int N = sc.nextInt();
		long[] B = new long[N - 1];
		for (int i = 0; i < N - 1; i++) {
			B[i] = sc.nextLong();
		}
		long ret = 0;
		long[] A = new long[N];
		A[0] = B[0];
		for (int i = 0; i < N - 1; i++) {
			A[i + 1] = B[i];
			if (i > 0 && A[i + 1] < A[i]) {
				A[i] = A[i + 1];
			}
		}
		for (int i = 0; i < N; i++) {
			ret += A[i];
		}
		System.out.println(ret);
	}

	public static List<String[]> Kumikae(List<String[]> list, int locate) {
		int sum = 0;
		int start = 0;
		int end = 0;
		String range = list.get(locate)[0] == "L" ? "R" : "L";
		if (locate != 0) {
			start = locate - 1;
			sum += Integer.parseInt(list.get(locate - 1)[1]);
		}
		if (locate == 0) {
			start = locate;
		}
		sum += Integer.parseInt(list.get(locate)[1]);
		end = locate;
		if (locate + 1 < list.size()) {
			end = locate + 1;
			sum += Integer.parseInt(list.get(locate + 1)[1]);
		}
		for (int i = end; i >= start; i--) {
			list.remove(i);
		}
		String[] a = new String[2];
		a[0] = range;
		a[1] = String.valueOf(sum);
		list.add(start, a);
		return list;
	}

	public static int getMaxDataLocation(List<String[]> list) {
		if (list.size() <= 2) {
			return 0;
		}
		int maxValue = Integer.parseInt(list.get(1)[1]);
		int locate = 1;
		for (int i = 2; i < list.size() - 1; i++) {
			int value = Integer.parseInt(list.get(i)[1]);
			if (maxValue < value) {
				maxValue = value;
				locate = i;
			}
		}
		return locate;
	}

	public static List<String[]> getRunLength(String str) {
		List<String[]> list = new ArrayList<String[]>();
		char back = 'm';
		for (int i = 0; i < str.length(); i++) {
			if (back != str.charAt(i)) {
				String[] hairetu = new String[2];
				hairetu[0] = String.valueOf(str.charAt(i));
				hairetu[1] = "1";
				list.add(hairetu);
				back = str.charAt(i);
			} else {
				String[] hairetu = list.get(list.size() - 1);
				hairetu[1] = String.valueOf(Integer.parseInt(hairetu[1]) + 1);
				list.set(list.size() - 1, hairetu);
			}
		}
		return list;
	}

}

class FScanner {
	private final InputStream in = System.in;
	private final byte[] buffer = new byte[1024];
	private int ptr = 0;
	private int buflen = 0;

	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		} else {
			ptr = 0;
			try {
				buflen = in.read(buffer);
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen <= 0) {
				return false;
			}
		}
		return true;
	}

	private int readByte() {
		if (hasNextByte())
			return buffer[ptr++];
		else
			return -1;
	}

	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}

	public boolean hasNext() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
		return hasNextByte();
	}

	public String next() {
		if (!hasNext())
			throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while (isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	public long nextLong() {
		if (!hasNext())
			throw new NoSuchElementException();
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while (true) {
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			} else if (b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			} else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}

	public int nextInt() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
			throw new NumberFormatException();
		return (int) nl;
	}

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

Measured memory_bytes: 22228