123. The sum
time limit per test: 0.25
sec. The Fibonacci sequence of numbers is known: F_{1} = 1; F_{2} = 1; F_{n+1} = F_{n} + F_{n1}, for n>1. You have to find S  the sum of the first K Fibonacci numbers. Input First line contains natural number K (0<K<41). Output First line should contain number S. Sample Input 5 Sample Output 12  
