snake_moves

rows, cols = [int(n) for n in input().split()]

text = input()
matrix = []

text_idx = 0

for row in range(rows):
    current_row = [''] * cols
    if row % 2 == 0:
        for col in range(cols):
            current_idx = text_idx % len(text)
            current_row[col] = text[current_idx]
            text_idx += 1

    else:
        for col in range(cols - 1, -1, -1):
            current_idx = text_idx % len(text)
            current_row[col] = text[current_idx]
            text_idx += 1
    matrix.append(current_row)
for r in range(rows):
    print(*matrix[r], sep='')