file_all = open("pths_students_all_list.txt", encoding="UTF-8")
data = file_all.readlines()
data2 = []
for line in data:
    data2.append(line.strip())
data = data2
count = [0] * 2022
for line in data:
    year = int(line[-6:-2])
    assert 1987 <= year <= 2021, line
    count[year] += 1
print(count)
max_graduates = max(count)
for year in range(len(count)):
    if count[year] == max_graduates:
        print(year)