There are two lists. Write a function that looks for matching values of these two lists. If a match is found, only the 2nd value must be replaced by replacing_num stnums = ['4004'] students = [ ['0001', 'Antonov', 'Anton', 'Igorevich', '20.08.2009', 'BST161'], ["1102", "Bogov", "Artem", "Igorevich", "25.01.2010", "BST162"] ["0333", "Glagoleva", "Anastasiya", "Nikolaevna", "11.07.2009", "BST163"] ["4004", "Stepanova", "Natalia", "Aleksandrovna", "13.02.2008", "BST161"] ["0045", "Bokov", "Igor", "Kharitonovich", "02.06.2009", "BST161"], ["0096", "Vasil'kov", "Valentin", "Sergeevich", "20.03.2009", "BST164"], ["0607", "Siropova", "Violetta", "Eduardovna", "28.05.2010", "BST162"], ["4004", "Potapov", "Dmitry", "Stanislavovich", "14.02.2012", "BST161"] ] replacing_num = '9090'

def replace_num(stnums, students, replacing_num):
    for num in stnums:
        for st in students:
            if st[0] == num:
                st[1] = replacing_num
    return students

replace_num(stnums, students, replacing_num)