How to make a cake you'll never eat.

Ingredients. 

  * 2 carrots
  * 0 calories
  * 100 g chocolate spread
  * 1 pack of flour
  * 1 egg



Method. 

  1. Put calories into the mixing bowl.
  2. Take carrots from refrigerator.
  3. Chop carrots.
  4. Take chocolate spread from refrigerator.
  5. Put chocolate spread into the mixing bowl.
  6. Combine pack of flour into the mixing bowl.
  7. Fold chocolate spread into the mixing bowl.
  8. Add chocolate spread into the mixing bowl.
  9. Put pack of flour into the mixing bowl.
  10. Add egg into the mixing bowl.
  11. Fold pack of flour into the mixing bowl.
  12. Chop carrots until choped.
  13. Pour contents of the mixing bowl into the baking dish.



Serves 1.

Input

The only line of input contains a sequence of integers a0, a1, ... (1 ≤ a0 ≤ 100, 0 ≤ ai ≤ 1000 for i ≥ 1).

Output

Output a single integer.

Examples

Input

4 1 2 3 4


Output

30
import java.io.*;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {

    FastScanner in;
    PrintWriter out;

    Main () {
        in = new FastScanner(IO_Type.CONSOLE).getScanner();
        out = new FastWriter(IO_Type.CONSOLE).getWriter();

        //in = new FastScanner(IO_Type.TEST, "test.txt").getScanner();
        //out = new FastWriter(IO_Type.TEST, "result.txt").getWriter();

        //in = new FastScanner(IO_Type.FILE, "input.txt").getScanner();
        //out = new FastWriter(IO_Type.TEST, "output.txt").getWriter();
    }

    public static void main (String[]args) {
        Main task = new Main();
        task.solve();
        task.close();
    }

    public void close () {
        in.close();
        out.close();
    }

    public void solve () {
        int n = in.nextInt();
        int sum = 0;
        for (int i = 0; i < n; i++) {
            sum += in.nextInt() * (i + 1);
        }
        out.println(sum);
    } 
}

class Algebra {
    /****
     *       Number of co-prime numbers on [1, n].
     *       Number a is Co-prime if gcd (a, n) == 1
     *       O (sqrt(n))
     ****/
    public static int phi(int n) {
        int result = n;
        for (int i = 2; i*i <= n; ++i) {
            if (n % i == 0) {
                while (n % i == 0) {
                    n /= i;
                }
                result -= result / i;
            }
        }
        if (n > 1) {
            result -= result / n;
        }
        return result;
    }

    /****
     *       Raise number a to power of n.
     *       O (log n)
     ****/
    public static int binpow (int a, int n) {
        int res = 1;
        while (n != 0) {
            if ((n & 1) == 1)
                res *= a;
            a *= a;
            n >>= 1;
        }
        return res;
    }

    /****
     *       Finding the greatest common divisor of two numbers.
     *       O (log min(a, b))
     ****/
    public static int gcd (int a, int b) {
        return (b != 0) ? gcd (b, a % b) : a;
    }

    /****
     *       Finding the lowest common multiple of two numbers.
     *       O (log min(a, b))
     ****/
    public static int lcm (int a, int b) {
        return a / gcd (a, b) * b;
    }

    /****
     *       Eratosthenes Sieve of numbers - [0..n]. True - simple, False - not simple.
     *       O (n log log n)
     ****/
    public static boolean[] sieveOfEratosthenes (int n) {
        boolean [] prime = new boolean[n + 1];
        Arrays.fill(prime, true);
        prime[0] = prime[1] = false;
        for (int i=2; i<=n; ++i) {
            if (prime[i]) {
                if (i * 1L * i <= n) {
                    for (int j=i*i; j<=n; j+=i) {
                        prime[j] = false;
                    }
                }
            }
        }
        return prime;
    }
}

class IO_Type {

    public static String CONSOLE = "console";
    public static String FILE = "file";
    public static String TEST = "test";

}

class FastScanner {

    BufferedReader br;
    StringTokenizer st;

    FastScanner getScanner() {
        return this;
    }

    FastScanner(String type) {
        if (type.equals("console")) {
            FastScanner(System.in);
        }        
    }
    
    FastScanner(String type, String inFileName) {
         if (type.equals("file")) {
             File f = new File(inFileName);
             try {
                 FastScanner(new FileInputStream(f));
             } catch (FileNotFoundException e) {
                 e.printStackTrace();
             }
         }
        else if (type.equals("test")) {
             File f = new File(inFileName);
             try {
                 FastScanner(new FileInputStream(f));
             } catch (FileNotFoundException e) {
                 e.printStackTrace();
             }
         }
    }
    
    void FastScanner(InputStream in) {
        br = new BufferedReader(new InputStreamReader(in));
    }
    
    String next() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                System.err.println(e);
                return "";
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    long nextLong() {
        return Long.parseLong(next());
    }

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

    float nextFloat() {
        return Float.parseFloat(next());
    }
    BigInteger nextBigInt() {
        return new BigInteger(next());
    }

    void close() {
        try {
            br.close();
        }
        catch (IOException e) {
        }
    }
}

class FastWriter {

    PrintWriter pw;

    PrintWriter getWriter() {
        return pw;
    }
    
    FastWriter(String type) {
        FastWriter(type);
    }
    
    FastWriter (String type, String outFileName) {
        FastWriter(type, outFileName);
    }

    PrintWriter FastWriter(String type) {
        if (type.equals("console")) {
            pw = new PrintWriter(System.out);
        }
        return pw;
    }

    PrintWriter FastWriter(String type, String outFileName) {
        if (type.equals("console")) {
            pw = new PrintWriter(System.out);
        }
        else if (type.equals("test")) {
            try {
                pw = new PrintWriter(new File(outFileName));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        else if (type.equals("file")) {
            try {
                pw = new PrintWriter(new File(outFileName));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        return pw;
    }

}
