from sys import stdin

def subgraftetthet(nabomatrise, startnode):
    n = len(nabomatrise)

    besokt = [False] * n

    besok(nabomatrise, startnode, besokt)
    
    noder = 0
    kanter = 0
    
    for node in range(0, n):
        if besokt[node] == False:
            noder += 1
            for nabonode in range(0, n):
                if nabomatrise[node][nabonode] == True and besokt[nabonode] == False:
                    kanter += 1
    
    if noder == 0:
        return 0.0
    else:
        return float(kanter) / float(noder**2)
    
def besok(nabomatrise, node, besokt):
    besokt[node] = True
    for nabonode in range(0, len(nabomatrise)):
        if nabomatrise[node][nabonode] == True and besokt[nabonode] == False:
            besok(nabomatrise, nabonode, besokt)

def main():
    n = int(stdin.readline())
    nabomatrise = [None] * n # rader
    for i in range(0, n):
        nabomatrise[i] = [False] * n # kolonner
        linje = stdin.readline()
        for j in range(0, n):
            nabomatrise[i][j] = (linje[j] == '1')
    for linje in stdin:
        start = int(linje)
        print "%.3f" % (subgraftetthet(nabomatrise, start) + 1E-12)

main()