def check_field(field):
    if field.count('o') != 20:
        return False
    cells = list(field)
    cells = [cells[x * 10: (x + 1) * 10] for x in range(0, 10)]
    ships = [1, 1, 1, 1, 2, 2, 2, 3, 3, 4]
    while ships:
        found = False
        for i in range(10):
            for j in range(10):
                if cells[i][j] == 'o':
                    i1, j1 = i, j
                    if j1 == 9 or cells[i1][j1 + 1] == ' ':  # если вертикальный
                        if i1 == 9 or cells[i1 + 1][j1] == ' ':  # если 1 палуба
                            p = 1
                        elif i1 + 1 == 9 or cells[i1 + 2][j1] == ' ':  # если 2 палубы
                            p = 2
                        elif i1 + 2 == 9 or cells[i1 + 3][j1] == ' ':  # если 3 палубы
                            p = 3
                        elif i1 + 3 != 9 and cells[i1 + 4][j1] == 'o':
                            return False
                        else:
                            p = 4
                        if p in ships:
                            ships.remove(p)
                        else:
                            return False
                        for k in range(p):
                            cells[i1 + k][j1] = ' '
                    else:
                        if j1 == 9 or cells[i1][j1 + 1] == ' ':  # если 1 палуба
                            p = 1
                        elif j1 + 1 == 9 or cells[i1][j1 + 2] == ' ':  # если 2 палубы
                            p = 2
                        elif j1 + 2 == 9 or cells[i1][j1 + 3] == ' ':  # если 3 палубы
                            p = 3
                        elif j1 + 3 != 9 and cells[i1][j1 + 4] == 'o':
                            return False
                        else:
                            p = 4
                        if p in ships:
                            ships.remove(p)
                        else:
                            return False
                        for k in range(p):
                            cells[i1][j1 + k] = ' '
                    found = True
                if found:
                    break
            if found:
                break
        if not found:
            return False

    return True