package chelper;

import java.util.Arrays;

import io.InputReader;
import io.OutputWriter;
import misc.GCJSolution;
import misc.SimpleSavingChelperSolution;


public class TaskA extends GCJSolution {

  public void solve(int testNumber, InputReader in, OutputWriter out) {
    wrapSolve(testNumber, in, out);
  }

  @Override
  public void solve(int testNumber) {
    int n = in.nextInt();
    int[] a = in.nextIntArray(n);

    char[][] map = new char[n * 2][n];
    for (int i = 0; i < n * 2; i++) {
      Arrays.fill(map[i], '.');
    }

    int maxRowUsed = 0;
    boolean ok = true;

    for (int i = 0; i < n; i++) {
      int src = i;
      int dest = 0;

      for (; dest < n; dest++) {
        if (a[dest] > 0) {
          a[dest]--;
          break;
        }
      }

      int y = 0;
      while (src != dest) {
        if (src == 0 || src == n - 1) {
          ok = false;
        }

        boolean dir = src < dest;
        map[y][src] = dir ? '\\' : '/';
        src += dir ? 1 : -1;

        y++;

        maxRowUsed = Math.max(maxRowUsed, y);
      }
    }

    maxRowUsed++;

    if (!ok) {
      out.println("IMPOSSIBLE");
      return;
    }

    out.println(maxRowUsed);
    for (int i = 0; i < maxRowUsed; i++) {
      for (int j = 0; j < n; j++) {
        out.print(map[i][j]);
      }
      out.println();
    }
  }
}