Vasya has a beautiful garden where wonderful fruit trees grow and yield fantastic harvest every year. But lately thieves started to sneak into the garden at nights and steal the fruit too often. Vasya can’t spend the nights in the garden and guard the fruit because there’s no house in the garden! Vasya had been saving in for some time and finally he decided to build the house. The rest is simple: he should choose in which part of the garden to build the house. In the evening he sat at his table and drew the garden’s plan. On the plan the garden is represented as a rectangular checkered field n × m in size divided into squares whose side length is 1. In some squares Vasya marked the trees growing there (one shouldn’t plant the trees too close to each other that’s why one square contains no more than one tree). Vasya wants to find a rectangular land lot a × b squares in size to build a house on, at that the land lot border should go along the lines of the grid that separates the squares. All the trees that grow on the building lot will have to be chopped off. Vasya loves his garden very much, so help him choose the building land lot location so that the number of chopped trees would be as little as possible.

Input

The first line contains two integers n and m (1 ≤ n, m ≤ 50) which represent the garden location. The next n lines contain m numbers 0 or 1, which describe the garden on the scheme. The zero means that a tree doesn’t grow on this square and the 1 means that there is a growing tree. The last line contains two integers a and b (1 ≤ a, b ≤ 50). Note that Vasya can choose for building an a × b rectangle as well a b × a one, i.e. the side of the lot with the length of a can be located as parallel to the garden side with the length of n, as well as parallel to the garden side with the length of m.

Output

Print the minimum number of trees that needs to be chopped off to select a land lot a × b in size to build a house on. It is guaranteed that at least one lot location can always be found, i. e. either a ≤ n and b ≤ m, or a ≤ m и b ≤ n.

Examples

Input

2 2
1 0
1 1
1 1


Output

0


Input

4 5
0 0 1 0 1
0 1 1 1 0
1 0 1 0 1
1 1 1 1 1
2 3


Output

2

Note

In the second example the upper left square is (1,1) and the lower right is (3,2).


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

public class ProblemB_45 {
	
	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_45().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);
		}
	}
	
	static class Utils {

		private Utils() {}

		public static void mergeSort(int[] a) {
			mergeSort(a, 0, a.length - 1);
		}

		private static void mergeSort(int[] a, int leftIndex, int rightIndex) {
			final int MAGIC_VALUE = 50;
			if (leftIndex < rightIndex) {
				if (rightIndex - leftIndex <= MAGIC_VALUE) {
					insertionSort(a, leftIndex, rightIndex);
				} else {
					int middleIndex = (leftIndex + rightIndex) / 2;
					mergeSort(a, leftIndex, middleIndex);
					mergeSort(a, middleIndex + 1, rightIndex);
					merge(a, leftIndex, middleIndex, rightIndex);
				}
			}
		}

		private static void merge(int[] a, int leftIndex, int middleIndex, int rightIndex) {
			int length1 = middleIndex - leftIndex + 1;
			int length2 = rightIndex - middleIndex;
			int[] leftArray = new int[length1];
			int[] rightArray = new int[length2];
			System.arraycopy(a, leftIndex, leftArray, 0, length1);
			System.arraycopy(a, middleIndex + 1, rightArray, 0, length2);
			for (int k = leftIndex, i = 0, j = 0; k <= rightIndex; k++) {
				if (i == length1) {
					a[k] = rightArray[j++];
				} else if (j == length2) {
					a[k] = leftArray[i++];
				} else {
					a[k] = leftArray[i] <= rightArray[j] ? leftArray[i++] : rightArray[j++];
				}
			}
		}

		private static void insertionSort(int[] a, int leftIndex, int rightIndex) {
			for (int i = leftIndex + 1; i <= rightIndex; i++) {
				int current = a[i];
				int j = i - 1;
				while (j >= leftIndex && a[j] > current) {
					a[j + 1] = a[j];
					j--;
				}
				a[j + 1] = current;
			}
		}

	}
	
	void solve() throws IOException{
		int n = readInt();
		int m = readInt();
		boolean[][] tree = new boolean[n][m];
		for (int i = 0; i < n; i++){
			for (int j = 0; j < m; j++){
				tree[i][j] = readInt() == 1;
			}
		}
		int a = readInt();
		int b = readInt();
		int min = n * m;
		for (int i = 0; i <= n - a; i++){
			for (int j = 0; j <= m - b; j++){
				int count = 0;
				for (int k = 0; k < a; k++){
					for (int l = 0; l < b; l++){
						if (tree[i+k][j+l]) count++;
					}
				}
				min = min(min, count);
			}
		}
		for (int i = 0; i <= n - b; i++){
			for (int j = 0; j <= m - a; j++){
				int count = 0;
				for (int k = 0; k < b; k++){
					for (int l = 0; l < a; l++){
						if (tree[i+k][j+l]) count++;
					}
				}
				min = min(min, count);
			}
		}
		out.print(min);
	}
	
	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;
					}
				}
			}
		}
	}
}

