Problem:
Score : 300 points

Problem Statement

Snuke and Raccoon have a heap of N cards. The i-th card from the top has the integer a_i written on it.

They will share these cards.
First, Snuke will take some number of cards from the top of the heap, then Raccoon will take all the remaining cards.
Here, both Snuke and Raccoon have to take at least one card.

Let the sum of the integers on Snuke's cards and Raccoon's cards be x and y, respectively.
They would like to minimize |x-y|.
Find the minimum possible value of |x-y|.

Constraints

2 \leq N \leq 2 \times 10^5

-10^{9} \leq a_i \leq 10^{9}

a_i is an integer.

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_{N}

Output

Print the answer.

Sample Input 1

6
1 2 3 4 5 6

Sample Output 1

1

If Snuke takes four cards from the top, and Raccoon takes the remaining two cards, x=10, y=11, and thus |x-y|=1. This is the minimum possible value.

Sample Input 2

2
10 -10

Sample Output 2

20

Snuke can only take one card from the top, and Raccoon can only take the remaining one card. In this case, x=10, y=-10, and thus |x-y|=20.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CS_AtCoder {
	class Program {
		static void Main(string[] args) {
			new Calc().Solve();
		}
	}
	public class Calc {
		Scan cin = new Scan();
		public void Solve() {
			var N = cin.ReadInt();
			var a = cin.ReadLine().Split(' ').Select(long.Parse).ToList();
			var sum = a.Sum();
			long nSum = a[0];
			long min = 100000000;
			if (N == 2) {
				Math.Abs(a[0] - a[1]).WL();
				return;
			}
			for (int i = 1; i <N-1; i++) {
				var kSum = sum - nSum;
				min = Math.Min(min, Math.Abs(nSum - kSum));
				nSum += a[i];
			}
			min.WL();
			return;
		}


	}

	public class Scan {
		public Scan() { }
		public int ReadInt() => int.Parse(Console.ReadLine());
		public int[] ReadInt(char separator) => Console.ReadLine().Split(separator).Select(int.Parse).ToArray();
		public double ReadDouble() => double.Parse(Console.ReadLine());
		public double[] ReadDouble(char separator) => Console.ReadLine().Split(separator).Select(double.Parse).ToArray();
		public long ReadLong() => long.Parse(Console.ReadLine());
		public long[] ReadLong(char separator) => Console.ReadLine().Split(separator).Select(long.Parse).ToArray();
		public string ReadLine() => Console.ReadLine();
		public string[] ReadLine(char separator) => Console.ReadLine().Split(separator).ToArray();
	}
	public static class Utils {
		public static string Docking<T>(this IEnumerable<T> collection,Func<T,string> filter = null) {
			StringBuilder sb = new StringBuilder();
			long Length = collection.Count();
			foreach (var item in collection.Select((v, i) => new { V = v, I = i })) {
				sb.Append(filter != null ? filter(item.V) : item.V.ToString());
			}
			return sb.ToString();
		}
		public static void WL(this object obj) => Console.WriteLine(obj);
		public static int IntParse(this string s) => int.Parse(s);
		public static int IntParse(this char c) => c - '0';
		public static List<int> SieveOfEratosthenes(int max) {
			int prime;
			double sqMax = Math.Sqrt(max);
			var prList = new List<int>();
			var srList = new List<int>();
			for (int i = 2; i < max+1; i++) {
				srList.Add(i);
			}
			do {
				prime = srList[0];
				prList.Add(prime);
				srList.RemoveAll(x => x % prime == 0);
			} while (prime<sqMax);
			prList.AddRange(srList);
			return prList;
		}
		public static long NCR(int n,int r) {
			long p = 1;
			for (int i = 1; i <=r; i++) {
				p = p * (n - i + 1) / i;
			}
			return p;
		}
	}
}