Rust Taskbook Level 9.5

Given a string of words, find the longest word in this string.

Let's say we have a date 22.02.2017. This date has 4 twos. Find all dates with 4 twos in the current century and write them in a vector.

Determine how many Fridays are 13-th in the current year.

Given a text file. Get a string consisting of the first letters of each line of the file. Write the found string to a new file.

Write a program that will generate the following string: