#!/usr/bin/python3

import sys

filename=(len(sys.argv) > 1) and sys.argv[1] or "22_10.txt"

cur_jolts=0
adaptors=[int(line.rstrip()) for line in open(filename, "r")]
adaptors.sort()
end_jolts=adaptors[-1]+3

diff_counts={}

for adaptor in adaptors:
    if adaptor-cur_jolts == 3:
        if 3 not in diff_counts:
            diff_counts[3]=0
        diff_counts[3]+=1
    elif adaptor-cur_jolts == 1:
        if 1 not in diff_counts:
            diff_counts[1]=0
        diff_counts[1]+=1
    else:
        raise Exception("Diff is not 1 or 3!")
    cur_jolts=adaptor

diff_counts[3]+=1
print(diff_counts)
print(diff_counts[1] * diff_counts[3])