Problem:
Score : 300 points

Problem Statement

We have a square grid with H rows and W columns.
Snuke wants to write 0 or 1 in each of the squares.
Here, all of the following conditions have to be satisfied:

For every row, the smaller of the following is A: the number of 0s contained in the row, and the number of 1s contained in the row. (If these two numbers are equal, “the smaller” should be read as “either”.)

For every column, the smaller of the following is B: the number of 0s contained in the column, and the number of 1s contained in the column.

Determine if these conditions can be satisfied by writing 0 or 1 in each of the squares. If the answer is yes, show one way to fill the squares so that the conditions are satisfied.

Constraints

1 \leq H,W \leq 1000

0 \leq A

2 \times A \leq W

0 \leq B

2 \times B \leq H

All values in input are integers.

Input

Input is given from Standard Input in the following format:

H W A B

Output

If the conditions cannot be satisfied by writing 0 or 1 in each of the squares, print -1.

If the conditions can be satisfied, print one way to fill the squares so that the conditions are satisfied, in the following format:

s_{11}s_{12}\cdots s_{1W}
s_{21}s_{22}\cdots s_{2W}
\vdots
s_{H1}s_{H2}\cdots s_{HW}

Here s_{ij} is the digit written in the square at the i-th row from the top and the j-th column from the left in the grid.

If multiple solutions exist, printing any of them will be accepted.

Sample Input 1

3 3 1 1

Sample Output 1

100
010
001

Every row contains two 0s and one 1, so the first condition is satisfied.
Also, every column contains two 0s and one 1, so the second condition is satisfied.

Sample Input 2

1 5 2 0

Sample Output 2

01010

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using static System.Math;
using System.Linq;
using System.Text;
 
class DandA {
    static void Main(string[] args) {
        int[] hwab = ReadLineIntArray();
        int[,] rtnArr = new int[hwab[0],hwab[1]];
        int wIndex = 0;
        for (int i = 0;i < hwab[0];i++) {
            int cnt = 0;
            while (cnt < hwab[2]) {
                rtnArr[i,wIndex]++;
                if (wIndex < hwab[1] - 1) {wIndex++;} else {wIndex = 0;}
                cnt++;
            }
        }
        
        for (int i = 0;i < hwab[1];i++) {
            int cnt = 0;
            for (int j = 0;j < hwab[0];j++) {
                cnt += rtnArr[j,i];
            }
            if (cnt != hwab[3] && (hwab[0] - cnt) != hwab[3]) {Console.WriteLine("No"); return;}
        }

        StringBuilder sb = new StringBuilder();
        for (int i = 0;i < hwab[0];i++) {
            for (int j = 0;j < hwab[1];j++) {
                sb.Append(rtnArr[i,j]);
            }
            sb.Append(Environment.NewLine);
        }
        Console.Write(sb.ToString());
    }
 
    static string alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
    static string[] strAry = new string[] {"L", "R", "U", "D"};
    static int[] intArray = new int[10];
    static List<int> intList = new List<int>();
    static Dictionary<string, int> myTable = new Dictionary<string, int>();
    static HashSet<int>[] rtnArrAb = null;
    static HashSet<int>[] rtnArrCd = null;
    static long[,] Combi = new long[2001,2001];
    static long div = 1000000007;
  
    static private string ReadLineStr() {return Console.ReadLine();}
    static private int ReadLineInt() {return int.Parse(Console.ReadLine());}
    static private long ReadLineLong() {return long.Parse(Console.ReadLine());}
    static private double ReadLineDouble() {return double.Parse(Console.ReadLine());}
    static private string[] ReadLineStrArray() {return Console.ReadLine().Trim().Split();}
    static private int[] ReadLineIntArray() {return Console.ReadLine().Trim().Split().Select(a => int.Parse(a)).ToArray();}
    static private long[] ReadLineLongArray() {return Console.ReadLine().Trim().Split().Select(a => long.Parse(a)).ToArray();}
    static private double[] ReadLineDoubleArray() {return Console.ReadLine().Trim().Split().Select(a => double.Parse(a)).ToArray();}
    static private decimal[] ReadLineDecimalArray() {return Console.ReadLine().Trim().Split().Select(a => decimal.Parse(a)).ToArray();}
    static private List<int> ReadLineIntList() {return Console.ReadLine().Trim().Split().Select(a => int.Parse(a)).ToList();}
    static private List<long> ReadLineLongList() {return Console.ReadLine().Trim().Split().Select(a => long.Parse(a)).ToList();}
    static private string[][] ReadMLineStrArray(int arg) { return new int[arg].Select(_ => Console.ReadLine().Split()).ToArray();}
    static private int[][] ReadMLineIntArray(int arg) { return new int[arg].Select(_ => Console.ReadLine().Split().Select(int.Parse).ToArray()).ToArray();}
 
    static private bool IsPrime(int num) {
        if (num < 2) return false;
        if (num == 2) return true;
        else if (num % 2 == 0) return false;
        double sqrtNum = Math.Sqrt(num);
        for (int i = 3; i <= sqrtNum; i += 2) {
            if (num % i == 0) return false;
        }
        return true;
    }
  
    static private string IntToNString(int x, int n) {
        var nstring = "";
        var numbers = new string[] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
        int r = 1;
        int q = x;
        while (q > 0) {
            r = q % n;
            nstring += numbers[r];
            q = q / n;
        }
        return string.Join("",nstring.Reverse());
    }
    static private long Gcd(long m,long n){
        long temp;
        while(m % n != 0) {
            temp = n;
            n = m % n;
            m = temp;
        }
        return n;
    }
 
    static private long Combination(long n,long r){
        if(n < r) {return 0;}
        if(n == r || r == 0) {return 1;}
        else if(Combi[n,r] == 0) {
            Combi[n,r] = (Combination(n-1,r-1)+Combination(n-1,r)) % div;
        }
        return Combi[n,r];
    }
}