import copy

def checksum(diskdump):
    out = 0
    for i in range(0,len(diskdump)):
        if diskdump[i] == ".":
            return out
        else:
            out += diskdump[i]*i

def abstToDump(abst):
    dump = []
    flag = True
    i = 0
    for a in abst:
        for j in range(0,int(a)):
            dump.append(i if flag else -1)
        flag = not flag
        i += 1 if not flag else 0
    return dump

def orderDump(dump):
    arr = ["."]*len(dump)
    i = 0
    for a in dump:
        if a == -1:
            if dump[-1] != -1:
                arr[i] = dump[-1]
                i += 1
            else:
                pass
            dump.pop(-1)
        else:
            arr[i] = a
            i += 1
    return arr

with open("input09.txt","r") as f:
    dump = abstToDump(f.read())
order = orderDump(copy.deepcopy(dump))
print(checksum(order))