def gravitation(rows):

    def checkMotless(rows):
        #returns needed steps until column becomes motionless
        motless = []
        bedrock = len(rows)-1
        for i in range(len(rows[0])):
            topind = 0
            botind = bedrock

            count = 0

            topLock = False
            botLock = False

            while not (topLock and botLock):
                if rows[botind][i] == '#':
                    botind = botind - 1
                if rows[botind][i] == '.':
                    botLock = True
                if rows[topind][i] == '.':
                    topind = topind + 1
                if rows[topind][i] == '#':
                    topLock = True
                if botind == topind:
                    topLock = True
                    botLock = True

            print(topind)
            print(botind)
            print("--")
            for k in range(topind+1,botind+1,1):
                if rows[k][i] == '.':
                    count = count + 1

            motless.append(count)
        return motless


    motless = checkMotless(rows)

    print(motless)

    ans = []
    mini = min(motless)

    for i in range(len(motless)):
        if motless[i]==mini:
            ans.append(i)

    return ans