## 习题
-1. [SPOJ #4141 "Euler Totient Function" [Difficulty: CakeWalk]](http://www.spoj.com/problems/ETF/)
-2. [UVA #10179 "Irreducible Basic Fractions" [Difficulty: Easy]](http://uva.onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=1120)
-3. [UVA #10299 "Relatives" [Difficulty: Easy]](http://uva.onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=1240)
-4. [UVA #11327 "Enumerating Rational Numbers" [Difficulty: Medium]](http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=2302)
-5. [TIMUS #1673 "Admission to Exam" [Difficulty: High]](http://acm.timus.ru/problem.aspx?space=1&num=1673)
+1. [SPOJ #4141 "Euler Totient Function" \[Difficulty: CakeWalk\]](http://www.spoj.com/problems/ETF/)
+2. [UVA #10179 "Irreducible Basic Fractions" \[Difficulty: Easy\]](http://uva.onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=1120)
+3. [UVA #10299 "Relatives" \[Difficulty: Easy\]](http://uva.onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=1240)
+4. [UVA #11327 "Enumerating Rational Numbers" \[Difficulty: Medium\]](http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=2302)
+5. [TIMUS #1673 "Admission to Exam" \[Difficulty: High\]](http://acm.timus.ru/problem.aspx?space=1&num=1673)