
    Given n delivery zones in a metropolitan area, determine the number of different ways to organize these zones into route groups for the delivery fleet, where each zone must be assigned to exactly one group and any number of groups is allowed. Each unique grouping arrangement represents a potential route distribution strategy that the fleet can adopt based on real-time traffic and weather conditions.
    

    
def bell_number(n):
    """
    Given n delivery zones in a metropolitan area, determine the number of different ways to organize these zones into route groups for the delivery fleet, where each zone must be assigned to exactly one group and any number of groups is allowed. Each unique grouping arrangement represents a potential route distribution strategy that the fleet can adopt based on real-time traffic and weather conditions.
    

    """
def bell_number(n):
    """
    Given n delivery zones in a metropolitan area, determine the number of different ways to organize these zones into route groups for the delivery fleet, where each zone must be assigned to exactly one group and any number of groups is allowed. Each unique grouping arrangement represents a potential route distribution strategy that the fleet can adopt based on real-time traffic and weather conditions.
    

    """
    bell = [[0 for i in range(n + 1)] for j in range(n + 1)]
    bell[0][0] = 1
    for i in range(1, n + 1):
        bell[i][0] = bell[i - 1][i - 1]
        for j in range(1, i + 1):
            bell[i][j] = bell[i - 1][j - 1] + bell[i][j - 1]
    return bell[n][0]