The average miner Vaganych took refresher courses. As soon as a miner completes the courses, he should take exams. The hardest one is a computer test called "Testing Pants for Sadness".

The test consists of n questions; the questions are to be answered strictly in the order in which they are given, from question 1 to question n. Question i contains ai answer variants, exactly one of them is correct. 

A click is regarded as selecting any answer in any question. The goal is to select the correct answer for each of the n questions. If Vaganych selects a wrong answer for some question, then all selected answers become unselected and the test starts from the very beginning, from question 1 again. But Vaganych remembers everything. The order of answers for each question and the order of questions remain unchanged, as well as the question and answers themselves.

Vaganych is very smart and his memory is superb, yet he is unbelievably unlucky and knows nothing whatsoever about the test's theme. How many clicks will he have to perform in the worst case?

Input

The first line contains a positive integer n (1 ≤ n ≤ 100). It is the number of questions in the test. The second line contains space-separated n positive integers ai (1 ≤ ai ≤ 109), the number of answer variants to question i.

Output

Print a single number — the minimal number of clicks needed to pass the test it the worst-case scenario. 

Please do not use the %lld specificator to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specificator.

Examples

Input

2
1 1


Output

2

Input

2
2 2


Output

5

Input

1
10


Output

10

Note

Note to the second sample. In the worst-case scenario you will need five clicks: 

  * the first click selects the first variant to the first question, this answer turns out to be wrong. 
  * the second click selects the second variant to the first question, it proves correct and we move on to the second question; 
  * the third click selects the first variant to the second question, it is wrong and we go back to question 1; 
  * the fourth click selects the second variant to the first question, it proves as correct as it was and we move on to the second question; 
  * the fifth click selects the second variant to the second question, it proves correct, the test is finished. 


import java.awt.Point;
import java.io.*;
import java.math.BigInteger;
import java.util.*;
import static java.lang.Math.*;

public class ProblemB_80 {
	
	final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE")!=null;
	BufferedReader in;
	PrintWriter out;
	StringTokenizer tok = new StringTokenizer("");
	
	void init() throws FileNotFoundException{
		if (ONLINE_JUDGE){
			in = new BufferedReader(new InputStreamReader(System.in));
			out = new PrintWriter(System.out);
		}else{
			in = new BufferedReader(new FileReader("input.txt"));
			out = new PrintWriter("output.txt");
		}
	}
	
	String readString() throws IOException{
		while(!tok.hasMoreTokens()){
			tok = new StringTokenizer(in.readLine());
		}
		return tok.nextToken();
	}
	
	int readInt() throws IOException{
		return Integer.parseInt(readString());
	}
	
	long readLong() throws IOException{
		return Long.parseLong(readString());
	}
	
	double readDouble() throws IOException{
		return Double.parseDouble(readString());
	}
	
	public static void main(String[] args){
		new ProblemB_80().run();
	}
	
	public void run(){
		try{
			long t1 = System.currentTimeMillis();
			init();
			solve();
			out.close();
			long t2 = System.currentTimeMillis();
			System.err.println("Time = "+(t2-t1));
		}catch (Exception e){
			e.printStackTrace(System.err);
			System.exit(-1);
		}
	}
	
	void solve() throws IOException{
		int n = readInt();
		long[] a = new long[n];
		for (int i = 0; i < n; i++){
			a[i] = readLong();
		}
		long s = 0;
		for (int i = 0; i < n; i++){
			s += (i + 1) * (a[i] - 1) + 1;
		}
		out.print(s);
	}
	
	static int[][] step8 = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}, {-1, -1}, {1, -1}, {-1, 1}, {1, 1}};
	
	static int[][] stepKnight = {{-2, -1}, {-2, 1}, {-1, -2}, {-1, 2}, {1, -2}, {1, 2}, {2, -1}, {2, 1}};
	
	static long gcd(long a, long b){
		if (a == 0)	return b;
		return gcd(b % a, a);
	}
	
	static long lcm(long a, long b){
		return a / gcd(a, b)*b;
	}

	static long[] gcdPlus(long a, long b){
		long[] d = new long[3];
		if (a == 0){
			d[0] = b;
			d[1] = 0;
			d[2] = 1;
		}else{
			d = gcdPlus(b % a, a);
			long r = d[1];
			d[1] = d[2] - b/a*d[1];
			d[2] = r;
		}
		return d;
	}
	
	static long binpow(long a, int n){
		if (n == 0)	return 1;
		if ((n & 1) == 0){
			long b = binpow(a, n/2);
			return b*b;
		}else return binpow(a, n - 1)*a;
	}
	
	static long binpowmod(long a, int n, long m){
		if (m == 1) return 0;
		if (n == 0)	return 1;
		if ((n & 1) == 0){
			long b = binpowmod(a, n/2, m);
			return (b*b) % m;
		}else return binpowmod(a, n - 1, m)*a % m;
	}
	
	static long phi(long n){
		int[] p = Sieve((int)ceil(sqrt(n)) + 2);
		long phi = 1;
		for (int i = 0; i < p.length; i++){
			long x = 1;
			while (n % p[i] == 0){
				n /= p[i];
				x *= p[i];
			}
			phi *= x - x/p[i];
		}
		if (n != 1) phi *= n - 1;
		return phi;
	}
	
	static long f(long n, int x, int k){ //���-�� ���������� ����� (������� 0), ���������� � ���� ����� �� 0 �� k-1
		if (n == 0)	return 1;
		long b = binpow(10, x - 1);
		long c = n / b;
		return (c < k? c: k)*binpow(k, x - 1) + (c < k? 1: 0)*f(n % b, x - 1, k);
	}
	
	static long fib(int n){
		if (n == 0) return 0;
		if ((n & 1) == 0){
			long f1 = fib(n/2 - 1);
			long f2 = fib(n/2 + 1);
			return f2*f2 - f1*f1;
		}else{
			long f1 = fib(n/2);
			long f2 = fib(n/2 + 1);
			return f1*f1 + f2*f2;
		}
	}
	
	static BigInteger BigFib(int n){
		if (n == 0) return BigInteger.ZERO;
		if ((n & 1) == 0){
			BigInteger f1 = BigFib(n/2 - 1);
			f1 = f1.multiply(f1);
			BigInteger f2 = BigFib(n/2 + 1);
			f2 = f2.multiply(f2);
			return f2.subtract(f1);
		}else{
			BigInteger f1 = BigFib(n/2);
			f1 = f1.multiply(f1);
			BigInteger f2 = BigFib(n/2 + 1);
			f2 = f2.multiply(f2);
			return f2.add(f1);
		}
	}
	
	static public class PointD{
		
		double x, y;
		
		public PointD(double x, double y){
			this.x = x;
			this.y = y;
		}
	}
	
	static double d(Point p1, Point p2){
		return sqrt(d2(p1, p2));
	}
	
	static public double d(PointD p1, PointD p2){
		return sqrt(d2(p1, p2));
	}
	
	static double d2(Point p1, Point p2){
		return (p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y);
	}
	
	static public double d2(PointD p1, PointD p2){
		return (p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y);
	}
	
	static boolean IsProbablyPrime(long n){
		if (n == 1)	return false;
		if ((n & 1) == 0) return false;
		for (int j = 3; j < sqrt(n) + 1; j += 2){
			if (n % j == 0)	return false;
		}
		return true;
	}

	static int[] Sieve(int n){
		boolean[] b = new boolean[n+1];
		Arrays.fill(b, true);
		b[0] = false;
		b[1] = false;
		long nLong = n;
		int j=0;
		for (int i = 1; i <= n; i++) {
			if (b[i]){
				j++;
				if (((long)i)*i <= nLong) {
					for (int k = i*i; k <= n; k += i) {
						b[k] = false;
					}
				}
			}
		}
		int[] p = new int[j];
		Arrays.fill(p, 0);
		j=0;
		for (int i = 2; i <= n; i++) {
			if (b[i]){
				p[j]=i;
				j++;
			}
		}
		return p;
	}
	
	static int[][] Palindromes(String s){
		char[] c = s.toCharArray();
		int n = c.length;
		int[][] d = new int[2][n];
		int l = 0, r = -1;
		for (int i = 0; i < n; i++){
			int j = (i > r? 0: min(d[0][l+r-i+1], r-i+1)) + 1;
			for (; i - j >= 0 && i + j - 1< n && c[i-j] == c[i+j-1]; j++);
			d[0][i] = --j;
			if (i + d[0][i] - 1 > r){
				r = i + d[0][i] - 1;
				l = i - d[0][i];
			}
		}
		l = 0;
		r = -1;
		for (int i = 0; i < n; i++){
			int j = (i > r? 0: min(d[1][l+r-i], r-i)) + 1;
			for (; i - j >= 0 && i + j < n && c[i-j] == c[i+j]; j++);
			d[1][i] = --j;
			if (i + d[1][i] > r){
				r = i + d[1][i];
				l = i - d[1][i];
			}
		}
		return d;
	}
	
	static public class Permutation {
		
		int[] a;
		int n;
		
		public Permutation(int n){
			this.n=n;
			a=new int[n];
			for (int i=0; i<n; i++){
				a[i]=i;
			}
		}
		
		public boolean nextPermutation(){ //������� � do{}while(nextPermutation(a));
			int i=n-1;
			for (i=n-2; i>=0; i--){
				if (a[i]<a[i+1]){
					break;
				}
			}
			if (i==-1){
				return false;
			}
			int jMin=i+1;
			for (int j=n-1; j>i; j--){
				if (a[i]<a[j]&&a[j]<a[jMin]){
					jMin=j;
				}
			}
			swap(i, jMin);
			for (int j=1; j<=(n-i)/2; j++){
				swap(i+j, n-j);
			}
			return true;
		}
		
		
		public int get(int i){
			return a[i];
		}
		
		void swap(int i, int j){
			int r=a[i];
			a[i]=a[j];
			a[j]=r;
		}
	}
	
	static public class Fraction implements Comparable<Fraction>, Cloneable{
		
		public final Fraction FRACTION_ZERO = new Fraction();
		public final Fraction FRACTION_ONE = new Fraction(1);
		public long numerator = 0;
		public long denominator = 1;
		
		public Fraction(){
			numerator = 0;
			denominator = 1;
		}
		
		public Fraction(long numerator){
			this.numerator = numerator;
			denominator = 1;
		}
		
		public Fraction(long numerator, long denominator){
			this.numerator = numerator;
			this.denominator = denominator;
			Cancellation();
		}
		
		public Fraction(double numerator, double denominator, int accuracy){
			this.numerator = (long)(numerator*pow(10,accuracy));
			this.denominator = (long)(denominator*pow(10,accuracy));
			Cancellation();
		}
		
		public Fraction(String s){
			if (s.charAt(0) == '-'){
				denominator = -1;
				s = s.substring(1);
			}
			if (s.indexOf("/") != -1){
				denominator *= Integer.parseInt(s.substring(s.indexOf("/") + 1));
			}
			if (s.indexOf(" ") != -1){
				numerator = Integer.parseInt(s.substring(0, s.indexOf(" "))) * abs(denominator) + Integer.parseInt(s.substring(s.indexOf(" ") + 1, s.indexOf("/")));
			}else{
				if (s.indexOf("/") != -1){
					numerator = Integer.parseInt(s.substring(0, s.indexOf("/")));
				}else{
					numerator = Integer.parseInt(s)*abs(denominator);
				}
			}
			this.Cancellation();
		}
		
		void Cancellation(){
			long g = gcd(abs(numerator), abs(denominator));
			numerator /= g;
			denominator /= g;
			if (denominator < 0){
				numerator *= -1;
				denominator *= -1;
			}
		}
		
		public String toString(){
			String s = "";
			if (numerator == 0){
				return "0";
			}
			if (numerator < 0){
				s += "-";
			}
			if (abs(numerator) >= denominator){
				s += Long.toString(abs(numerator) / denominator) + " ";
			}
			if (abs(numerator) % denominator != 0){
				s += Long.toString(abs(numerator) % denominator);
			}else{
				s = s.substring(0, s.length()-1);
			}
			if (denominator != 1){
				s += "/" + Long.toString(denominator);
			}
			return s;
		}
		
		public Fraction add(Fraction f){
			Fraction fResult = new Fraction();
			fResult.denominator = lcm(denominator, f.denominator);
			fResult.numerator = numerator * fResult.denominator / denominator + f.numerator * fResult.denominator / f.denominator;
			fResult.Cancellation();
			return fResult;
		}
		
		public Fraction subtract(Fraction f){
			Fraction fResult = new Fraction();
			fResult.denominator = lcm(denominator, f.denominator);
			fResult.numerator = numerator * fResult.denominator / denominator - f.numerator * fResult.denominator / f.denominator;
			fResult.Cancellation();
			return fResult;
		}
		
		public Fraction multiply(Fraction f){
			Fraction fResult = new Fraction();
			fResult.numerator = numerator * f.numerator;
			fResult.denominator = denominator * f.denominator;
			fResult.Cancellation();
			return fResult;
		}
		
		public Fraction divide(Fraction f){
			Fraction fResult = new Fraction();
			fResult.numerator = numerator * f.denominator;
			fResult.denominator = denominator * f.numerator;
			fResult.Cancellation();
			return fResult;
		}
		
		@Override
		public int compareTo(Fraction f){
			long g = gcd(denominator, f.denominator);
			long res = numerator * (f.denominator / g) - f.numerator * (denominator / g);
			if (res < 0){
				return -1;
			}
			if (res > 0){
				return 1;
			}
			return 0;
		}
		
		public Fraction clone(){
			Fraction fResult = new Fraction(numerator, denominator);
			return fResult;
		}
		
		public Fraction floor(){
			Fraction fResult = this.clone();
			fResult.numerator = (fResult.numerator / fResult.denominator) * fResult.denominator;
			return fResult;
		}
		
		public Fraction ceil(){
			Fraction fResult = this.clone();
			fResult.numerator = (fResult.numerator/fResult.denominator + 1) * fResult.denominator;
			return fResult;
		}
		
		public Fraction binpow(int n){
			if (n==0) return FRACTION_ONE;
			if ((n&1)==0){
				Fraction f=this.binpow(n/2);
				return f.multiply(f);
			}else return binpow(n-1).multiply(this);
		}
	}
	
	static public class FenwickTree_1{	//One-dimensional array		
		
		int n;
		long[] t;
		
		public FenwickTree_1(int n){
			this.n = n;
			t = new long[n];
		}
		
		public long sum(int xl, int xr){
			return sum(xr) - sum(xl);
		}
		
		public long sum(int x){
			long result = 0;
			for (int i = x; i >= 0; i = (i & (i + 1)) - 1){
				result += t[i];
			}
			return result;
		}
		
		public void update(int x, long delta){
			for (int i = x; i < n; i = (i | (i + 1))){
				t[i] += delta;
			}
		}
	}
	
	static public class FenwickTree_2{	//Two-dimensional array
		
		int n, m;
		long[][] t;
		
		public FenwickTree_2(int n, int m){
			this.n = n;
			this.m = m;
			t = new long[n][m];
		}
		
		public long sum(int xl, int yl, int xr, int yr){
			return sum(xr, yr) - sum(xl - 1, yr) - sum(xr, yl - 1) + sum(xl - 1, yl - 1);
		}
		
		public long sum(int x, int y){
			long result = 0;
			for (int i = x; i >= 0; i = (i & (i + 1)) - 1){
				for (int j = y; j >= 0; j = (j & (j + 1)) - 1){
					result+=t[i][j];
				}
			}
			return result;
		}
		
		public void update(int x, int y, long delta){
			for (int i = x; i < n; i = (i | (i + 1))){
				for (int j = y; j < m; j = (j | (j + 1))){
					t[i][j] += delta;
				}
			}
		}
	}
	
	static public class FenwickTree_3{	//Three-dimensional array
		
		int n, m, l;
		long[][][] t;
		
		public FenwickTree_3(int n, int m, int l){
			this.n = n;
			this.m = m;
			this.l = l;
			t = new long[n][m][l];
		}
		
		public long sum(int xl, int yl, int zl, int xr, int yr, int zr){
			return sum(xr, yr, zr) - sum(xl - 1, yr, zr)
			+ sum(xl - 1, yr, zl - 1) - sum(xr, yr, zl - 1)
			- sum(xr, yl - 1, zr) + sum(xl - 1, yl - 1, zr)
			- sum(xl - 1, yl - 1, zl - 1) + sum(xr, yl - 1, zl - 1);
		}
		
		public long sum(int x, int y, int z){
			long result = 0;
			for (int i = x; i >= 0; i = (i & (i + 1)) - 1){
				for (int j = y; j >= 0; j = (j & (j + 1)) - 1){
					for (int k = z; k >= 0; k = (k & (k + 1)) - 1){
						result += t[i][j][k];
					}
				}
			}
			return result;
		}
		
		public void update(int x, int y, int z, long delta){
			for (int i = x; i < n; i = (i | (i + 1))){
				for (int j = y; j < n; j = (j | (j + 1))){
					for (int k = z; k < n; k = (k | (k + 1))){
						t[i][j][k] += delta;
					}
				}
			}
		}
	}
}

