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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.util.NoSuchElementException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FasterScanner in = new FasterScanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        public void solve(int testNumber, FasterScanner in, PrintWriter out) {
            final int n = in.nextInt();
            long[] a = new long[n - 1];

            a[0] = in.nextLong();
            for (int i = 1; i < n - 1; i++) a[i] = a[i - 1] + in.nextLong();
            long max = a[n - 2] + in.nextLong();

            int ansIndex = Search.lowerBound(a, max / 2);

            out.println(Math.abs(max - a[ansIndex] - a[ansIndex]));
        }

    }

    static class FasterScanner {
        private InputStream in;
        private byte[] buffer;
        private int bufPointer;
        private int bufLength;

        public FasterScanner(InputStream in) {
            this.in = in;
            buffer = new byte[1024];
        }

        private boolean hasNextByte() {
            if (bufPointer < bufLength) return true;
            bufPointer = 0;
            try {
                bufLength = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            return (bufLength > 0);
        }

        private int readByte() {
            if (hasNextByte()) return buffer[bufPointer++];
            return -1;
        }

        private static boolean isPrintableChar(int c) {
            return (c >= 33 && c <= 126);
        }

        public boolean hasNext() {
            while (hasNextByte() && !isPrintableChar(buffer[bufPointer])) bufPointer++;
            return hasNextByte();
        }

        public int nextInt() {
            long nl = nextLong();
            if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
            return (int) nl;
        }

        public long nextLong() {
            if (!hasNext()) throw new NoSuchElementException();
            long n = 0;
            boolean minus = false;
            int b = readByte();
            if (b == '-') {
                minus = true;
                b = readByte();
            }
            if (b < '0' || b > '9') throw new NumberFormatException();

            while (true) {
                if (b >= '0' && b <= '9') {
                    n *= 10;
                    n += b - '0';
                } else if (b == -1 || !isPrintableChar(b)) {
                    return minus ? -n : n;
                } else {
                    throw new NumberFormatException();
                }
                b = readByte();
            }
        }

    }

    static class Search {
        public static int lowerBound(long[] list, long lim) {
            int min = 0;
            int max = list.length - 1;
            while (true) {
                int mid = (min + max) / 2;
                if (mid == max || mid == min) break;
                if (list[mid] >= lim) max = mid;
                else min = mid;
            }
            return (list[min] >= lim) ? min : max;
        }

    }
}