#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
inline void chkmin(T1 &x, T2 y) {
  if (x > y) x = y;
}
template <typename T1, typename T2>
inline void chkmax(T1 &x, T2 y) {
  if (x < y) x = y;
}
inline int readChar();
template <class T = int>
inline T readInt();
template <class T>
inline void writeInt(T x, char end = 0);
inline void writeChar(int x);
inline void writeWord(const char *s);
static const int buf_size = 4096;
inline int getChar() {
  static char buf[buf_size];
  static int len = 0, pos = 0;
  if (pos == len) pos = 0, len = fread(buf, 1, buf_size, stdin);
  if (pos == len) return -1;
  return buf[pos++];
}
inline int readChar() {
  int c = getChar();
  while (c <= 32) c = getChar();
  return c;
}
template <class T>
inline T readInt() {
  int s = 1, c = readChar();
  T x = 0;
  if (c == '-') s = -1, c = getChar();
  while ('0' <= c && c <= '9') x = x * 10 + c - '0', c = getChar();
  return s == 1 ? x : -x;
}
static int write_pos = 0;
static char write_buf[buf_size];
inline void writeChar(int x) {
  if (write_pos == buf_size)
    fwrite(write_buf, 1, buf_size, stdout), write_pos = 0;
  write_buf[write_pos++] = x;
}
template <class T>
inline void writeInt(T x, char end) {
  if (x < 0) writeChar('-'), x = -x;
  char s[24];
  int n = 0;
  while (x || !n) s[n++] = '0' + x % 10, x /= 10;
  while (n--) writeChar(s[n]);
  if (end) writeChar(end);
}
inline void writeWord(const char *s) {
  while (*s) writeChar(*s++);
}
struct Flusher {
  ~Flusher() {
    if (write_pos) fwrite(write_buf, 1, write_pos, stdout), write_pos = 0;
  }
} flusher;
int n, m;
int a[3001];
pair<int, int> arr[3001];
char ans[3001][3001];
int s[3001];
int main() {
  n = readInt(), m = readInt();
  int sum = n * (n - 1);
  for (int i = 0; i < m; i++) {
    a[i] = readInt();
    sum -= a[i];
  }
  int cur = 0;
  for (int i = n - 1; i >= m; i--) {
    a[i] = (n - i) * (n - i - 1) - cur;
    cur += a[i];
  }
  sum -= cur;
  for (int i = m; i < n && sum > 0; i++) {
    int c = a[i - 1] - a[i];
    c = min(c, sum);
    sum -= c;
    a[i] += c;
  }
  if (a[m] > a[m - 1] || sum != 0) {
    writeWord("no\n");
    return 0;
  }
  writeWord("yes\n");
  for (int i = 0; i < n; i++) {
    arr[i].first = a[i];
    arr[i].second = i;
  }
  for (int i = 0; i < n; i++) {
    sort(arr + i, arr + n);
    int j = i + 1;
    while (j < n) {
      if (arr[i].first > 0) {
        arr[i].first--;
        arr[j].first--;
        ans[arr[i].second][arr[j].second] = 1;
        ans[arr[j].second][arr[i].second] = 1;
        j++;
      } else {
        arr[j].first -= 2;
        ans[arr[i].second][arr[j].second] = 0;
        ans[arr[j].second][arr[i].second] = 2;
        j++;
      }
    }
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (i == j) {
        writeChar('X');
      } else {
        if (ans[i][j] == 2) {
          writeChar('W');
        } else {
          if (ans[i][j] == 1) {
            writeChar('D');
          } else {
            writeChar('L');
          }
        }
      }
    }
    writeChar('\n');
  }
  return 0;
}
