URI Online Judge | 2495

# Where is my Pen?

By Juliany Rodrigues Raiol, UEA Brazil

Timelimit: 1

At the end of last month, I bought a set with N pens. It cost about 1/3 of my allowance, and on account of that, I decided to tell all my friends that I would not lend it to anyone. But last week, my cousin Jean borrowed it, saying she was going to give it back to me the next morning. Since she is family and would return soon, I decided to make an exception for her and end her all of them. Yes, I regretted it. Jean only gave it back to me this morning! I got it back, I checked if everything was in order. No, I was not! I noticed there were N-1 pens in my set. Since I was in a hurry to go to college, I ask you, Billie, to help me find which pen is missing. Consider that all pens are identified by integers in the interval [1, N]. I hope the pen that is missing is only lost! I can not stand the idea of Jean stealing from me!

## Input

The input is composed of several test cases. The first line has an integer N, where 2 ≤ N ≤ 105, indicating the number of pens in my set. The next lines are composed of integers N-1, indicating which pens were returned. For each terminating Ni of this sequence, consider that they are in the range of 1 ≤ Ni N.

## Output

The output is composed of a single line indicating which pen was not in the set.

 Input Sample Output Sample 50 14 17 16 48 15 43 1 33 49 2 8 41 21 6 30 35 37 32 50 40 13 34 12 5 39 9 47 4 46 18 23 31 7 24 10 3 42 29 19 45 27 25 38 26 44 36 22 11 28 40 16 26 15 36 37 38 20 40 23 19 24 1 22 13 2 9 7 29 39 30 21 3 18 17 35 27 11 5 8 6 12 25 14 4 31 28 34 32 33 10 5 2 3 1 6 8 4 9 7 20 10 10