""" description: given a music set, select a pair of musics and the sum of these two musics's duration is right minutes (divisible by 60) example 1: input: [20 40 60] output: 1 (20,40) example 2: input: [20 40 60 120] output: 2 (20,40),(60,120) """ """ 基本思想： 这是一个有限的组合匹配问题，暴力搜索的复杂度是O(n^2)，使用直方图统计每一个长度的音乐的个数，然后进行组合，注意长度为60的倍数的音乐和长度为30的音乐要特殊处理，负责度是O(n) """ import sys playlist=[20, 40, 60, 60, 120, 30, 30, 30, 60, 29, 31, 28, 32, 1, 59] def get_num(playlist): hist = [int(0)]*60 for data in playlist: hist[int(data%60)] += 1 num = int(0) for idx in range(30-1): num += hist[idx+1]*hist[59-idx] #29 num += hist[30]*(hist[30]-1)/2 + hist[0]*(hist[0]-1)/2 return int(num) if __name__ == "__main__": playlist = eval(sys.stdin.readline().strip()) print(get_num(playlist))