Puzzle-club president Dip is prepping brain-teasers for the club's game night. Warm-up: compute a large Fibonacci number efficiently, without letting recursion blow the stack. Read N. Print the N-th Fibonacci number (F(1)=1, F(2)=1) using an iterative DP array or two rolling variables — NOT plain recursion (too slow for large N).
Input
One integer N.
Output
F(N).
Constraints
1 ≤ N ≤ 90
Sample Input
10
Sample Output
55
main.c
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