n = 13
MOD = 26
grid = [[0] * n for _ in range(n)]
for i in range(n):
    for j in range(n):
        if i == j == 0:
            continue
        if j == 0:
            grid[i][j] = (grid[i - 1][j] + i + 1) % MOD
        else:
            grid[i][j] = (grid[i][j - 1] + i + j) % MOD

"""
se = set()
for i in range(n):
    for j in range(n):
        if i != n - 1:
            tmp = grid[i][j] * 100 + grid[i + 1][j]
            if tmp in se:
                print("=========")
            se.add(tmp)
        if j != n - 1:
            tmp = grid[i][j] * 100 + grid[i][j + 1]
            if tmp in se:
                print("=========")
            se.add(tmp)
"""

def f(x):
    return chr(x + 97)
print(n)            
for row in grid:
    print("".join(map(f, row)))