One day Vitaly was going home late at night and wondering: how many people aren't sleeping at that moment? To estimate, Vitaly decided to look which windows are lit in the house he was passing by at that moment.

Vitaly sees a building of n floors and 2·m windows on each floor. On each floor there are m flats numbered from 1 to m, and two consecutive windows correspond to each flat. If we number the windows from 1 to 2·m from left to right, then the j-th flat of the i-th floor has windows 2·j - 1 and 2·j in the corresponding row of windows (as usual, floors are enumerated from the bottom). Vitaly thinks that people in the flat aren't sleeping at that moment if at least one of the windows corresponding to this flat has lights on.

Given the information about the windows of the given house, your task is to calculate the number of flats where, according to Vitaly, people aren't sleeping.

Input

The first line of the input contains two integers n and m (1 ≤ n, m ≤ 100) — the number of floors in the house and the number of flats on each floor respectively.

Next n lines describe the floors from top to bottom and contain 2·m characters each. If the i-th window of the given floor has lights on, then the i-th character of this line is '1', otherwise it is '0'.

Output

Print a single integer — the number of flats that have lights on in at least one window, that is, the flats where, according to Vitaly, people aren't sleeping.

Examples

Input

2 2
0 0 0 1
1 0 1 1


Output

3


Input

1 3
1 1 0 1 0 0


Output

2

Note

In the first test case the house has two floors, two flats on each floor. That is, in total there are 4 flats. The light isn't on only on the second floor in the left flat. That is, in both rooms of the flat the light is off.

In the second test case the house has one floor and the first floor has three flats. The light is on in the leftmost flat (in both windows) and in the middle flat (in one window). In the right flat the light is off.
import javafx.util.Pair;

import java.io.*;
import java.util.*;

public class Main {
    private final static InputReader ir = new InputReader(System.in);
    private final static OutputWriter ow = new OutputWriter(System.out);
    private final static int INF = Integer.MAX_VALUE;
    private final static int NINF = Integer.MIN_VALUE;
    private final static double PI = Math.PI;

    public static void main(String[] args) throws IOException {
        try {
            task();
        } finally {
            boolean exc = false;
            try {
                ir.close();
            } catch (IOException e) {
                e.printStackTrace();
                exc = true;
            }
            try {
                ow.close();
            } catch (IOException e) {
                e.printStackTrace();
                exc = true;
            }
            if (exc) System.exit(1);
        }
    }

    private static void task() throws IOException {
        int n = ir.nextInt(), m = ir.nextInt();

        int ans = 0;
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < m; ++j) {

//                if (ir.nextInt() == 1 || ir.nextInt() == 1)
//                    ++ans;
                int f = ir.nextInt(), s = ir.nextInt();
                if (f == 1 || s == 1)
                    ++ans;
            }
        }
        ow.print(ans);
        /*
        boolean[] array = new boolean[10001];

        for (int i = 0; i <= 10000; ++i)
            array[i] = true;

        for (int i = 2; i <= 100; ++i) {
            if (array[i]) {
                for (int j = i; j <= 10000 / i; ++j) {
                    array[j * i] = false;
                }
            }
        }
        int cnt = 0;
        for (int i = 2; i <= 10000; ++i)
            if (array[i]) ++cnt;
        ow.println(cnt);

        for (int i = 0; i <= 10000; ++i)
            array[i] = true;

        for (int i = 2; i <= 100; ++i) {
            if (array[i]) {
                for (int j = i * i; j <= 10000; j += i) {
                    array[j] = false;
                }
            }
        }

        cnt = 0;
        for (int i = 2; i <= 10000; ++i)
            if (array[i]) ++cnt;
        ow.println(cnt);
//        for (int i = 0; i < 10000; ++i)
//            if (array[i])
//                ow.println(i);

*/
    }

    private static int max(int... objects) {
        if (objects.length == 0)
            throw new IllegalArgumentException("objects.length == 0");
        int max = objects[0];
        for (int i = 1; i < objects.length; ++i) {
            if (max < objects[i])
                max = objects[i];
        }
        return max;
    }

    private static int min(int... objects) {
        if (objects.length == 0)
            throw new IllegalArgumentException("objects.length == 0");
        int min = objects[0];
        for (int i = 1; i < objects.length; ++i) {
            if (min > objects[i])
                min = objects[i];
        }
        return min;
    }

    private static long pow(int x, int n) {
        if (x == 0) return 0;
        if (x == 1 || n == 0) return 1;
        if (n == 1) return x;
        long t = pow(x, n / 2);
        if (n % 2 == 0) return t * t;
        else return t * t * x;
    }

    private static int abs(int a) {
        return (a >= 0 ? a : -a);
    }
}

class SQRTDecomposition {
    private int[] array;
    private int len;
    private int[] max;
    private int[] min;

    public SQRTDecomposition(int[] arr) {
        array = new int[arr.length];
        System.arraycopy(arr, 0, array, 0, arr.length);
        len = (int) Math.sqrt(array.length) + 1;
        max = new int[len];
        min = new int[len];
        for (int i = 0; i < array.length; ++i) {
            max[i / len] = min[i / len] = array[i];
        }
        for (int i = 0; i < array.length; ++i) {
            max[i / len] = Math.max(max[i / len], array[i]);
            min[i / len] = Math.min(min[i / len], array[i]);
        }
    }

    public int get(int i) {
        if (i <= 0 || i >= array.length)
            throw new IndexOutOfBoundsException("Index: " + i);
        return array[i];
    }

    public int length() {
        return array.length;
    }

    public int max(int l, int r) {
        int cl = l / len, cr = r / len;
        int m = array[l];
        if (cl == cr) {
            for (int i = l; i <= r; ++i) {
                if (array[i] > m) m = array[i];
            }
        } else {
            for (int i = l, end = (cl + 1) * len - 1; i <= end; ++i)
                if (array[i] > m) m = array[i];
            for (int i = cl + 1; i <= cr - 1; ++i)
                if (max[i] > m) m = max[i];
            for (int i = cr * len; i <= r; ++i)
                if (array[i] > m) m = array[i];
        }
        return m;
    }

    public int min(int l, int r) {
        int cl = l / len, cr = r / len;
        int m = array[l];
        if (cl == cr) {
            for (int i = l; i <= r; ++i) {
                if (array[i] < m) m = array[i];
            }
        } else {
            for (int i = l, end = (cl + 1) * len - 1; i <= end; ++i)
                if (array[i] < m) m = array[i];
            for (int i = cl + 1; i <= cr - 1; ++i)
                if (min[i] < m) m = min[i];
            for (int i = cr * len; i <= r; ++i)
                if (array[i] < m) m = array[i];
        }
        return m;
    }
}

class InputReader implements AutoCloseable {
    private final InputStream in;
    private int capacity;
    private byte[] buffer;
    private int len = 0;
    private int cur = 0;

    public InputReader(InputStream stream) {
        this(stream, 100_000);
    }

    public InputReader(InputStream stream, int capacity) {
        this.in = stream;
        this.capacity = capacity;
        buffer = new byte[capacity];
    }

    private int read() {
        if (cur >= len) {
            try {
                cur = 0;
                len = in.read(buffer, 0, capacity);
                if (len <= 0)
                    return -1;
            } catch (IOException e) {
                throw new InputMismatchException();
            }
        }
        return buffer[cur++];
    }

    private boolean isSpace(int c) {
        return c == ' ' || isEscape(c);
    }

    private boolean isEscape(int c) {
        return c == '\n' || c == '\t' || c == '\r' || c == -1;
    }

    private int readSkipSpace() {
        int c;
        do {
            c = read();
        } while (isSpace(c));
        return c;
    }

    int nextInt() {
        int c = readSkipSpace();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        int res = 0;
        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res = res * 10 + c - '0';
            if (res < 0)
                throw new InputMismatchException();
            c = read();
        } while (!isSpace(c));
        res *= sgn;
        return res;
    }

    public long nextLong() {
        int c = readSkipSpace();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        long res = 0;
        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res = res * 10 + c - '0';
            if (res < 0)
                throw new InputMismatchException();
            c = read();
        } while (!isSpace(c));
        res *= sgn;
        return res;
    }

    int nextChar() {
        return readSkipSpace();
    }

    String nextLine(int initialCapacity) {
        StringBuilder res = new StringBuilder(initialCapacity);
        int c = readSkipSpace();
        do {
            res.append((char) (c));
            c = read();
        } while (!isEscape(c));
        return res.toString();
    }

    @Override
    public void close() throws IOException {
        in.close();
    }
}

class OutputWriter implements Flushable, AutoCloseable {
    private byte[] buf;
    private int capacity;
    private int count;
    private OutputStream out;

    public OutputWriter(OutputStream stream) {
        out = stream;
        capacity = 10_000;
        buf = new byte[capacity];
    }

    public OutputWriter(OutputStream stream, int capacity) {
        if (capacity <= 0)
            throw new IllegalArgumentException("capacity <= 0");
        out = stream;
        this.capacity = capacity;
        buf = new byte[capacity];
    }

    public void write(int b) throws IOException {
        if (count >= buf.length)
            flushBuffer();
        buf[count++] = (byte) b;
    }

    public void write(byte[] bytes, int off, int len) throws IOException {
        if (len >= buf.length) {
            flushBuffer();
            out.write(bytes, off, len);
            return;
        }
        if (len > buf.length - count)
            flushBuffer();
        System.arraycopy(bytes, off, buf, count, len);
        count += len;
    }

    public void write(byte[] bytes) throws IOException {
        write(bytes, 0, bytes.length);
    }

    public void print(String str) throws IOException {
        write(str.getBytes());
    }

    public void println() throws IOException {
        print("\n");
    }

    public void print(Object object) throws IOException {
        print(object.toString());
    }

    public void println(Object object) throws IOException {
        print(object.toString());
        println();
    }

    public void print(int... ints) throws IOException {
        print(" ", ints);
    }

    public void println(int... ints) throws IOException {
        print(ints);
        println();
    }

    public void println(String separator, int... ints) throws IOException {
        print(separator, ints);
        println();
    }

    public void print(String separator, int... ints) throws IOException {
        if (ints.length == 0) throw new IllegalArgumentException("ints.length == 0");
        for (int i = 0; i < ints.length; ++i) {
            if (i != 0) print(separator);
            print(ints[i]);
        }
    }

    private void flushBuffer() throws IOException {
        if (count > 0) {
            out.write(buf, 0, count);
            count = 0;
        }
    }

    @Override
    public void flush() throws IOException {
        flushBuffer();
        out.flush();
    }

    @Override
    public void close() throws IOException {
        flush();
        out.close();
    }
}





