import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;

public class Main {

	static PrintWriter out;
	static InputReader ir;
	static boolean debug = false;

	static void solve() {
		int n = ir.nextInt();
		long[] a = ir.nextLongArray(n);
		long[] b = new long[n + 1];
		for (int i = 0; i < n; i++) {
			b[i + 1] = a[i];
			b[i + 1] += b[i];
		}
		long mi = Long.MAX_VALUE;
		for (int i = 2; i <= n - 2; i++) {
			long[] ret = new long[4];
			int idx = lower_bound(b, 0, i, b[i] / 2);
			int p = Math.max(1, idx - 1);
			int q = Math.min(i - 1, idx);
			if (Math.abs(b[i] - 2 * b[p]) >= Math.abs(b[i] - 2 * b[q])) {
				ret[0] = b[q];
				ret[1] = b[i] - b[q];
			} else {
				ret[0] = b[p];
				ret[1] = b[i] - b[p];
			}
			idx = lower_bound(b, i, n, (b[n] + b[i]) / 2);
			p = Math.max(i + 1, idx - 1);
			q = Math.min(n - 1, idx);
			if (Math.abs(b[n] + b[i] - 2 * b[p]) >= Math.abs(b[n] + b[i] - 2 * b[q])) {
				ret[2] = b[q] - b[i];
				ret[3] = b[n] - b[q];
			} else {
				ret[2] = b[p] - b[i];
				ret[3] = b[n] - b[p];
			}
			Arrays.sort(ret);
			tr(ret);
			mi = Math.min(mi, ret[3] - ret[0]);
		}
		out.println(mi);
	}

	public static int lower_bound(long[] a, int fromIndex, int toIndex, long val) {
		if (val > a[toIndex])
			return toIndex + 1;
		if (val <= a[fromIndex])
			return fromIndex;
		int lb = fromIndex - 1, ub = toIndex;
		while (ub - lb > 1) {
			int mid = (ub - lb) / 2 + lb;
			if (a[mid] >= val) {
				ub = mid;
			} else {
				lb = mid;
			}
		}
		return ub;
	}

	public static void main(String[] args) {
		ir = new InputReader(System.in);
		out = new PrintWriter(System.out);
		solve();
		out.flush();
	}

	static class InputReader {

		private InputStream in;
		private byte[] buffer = new byte[1024];
		private int curbuf;
		private int lenbuf;

		public InputReader(InputStream in) {
			this.in = in;
			this.curbuf = this.lenbuf = 0;
		}

		public boolean hasNextByte() {
			if (curbuf >= lenbuf) {
				curbuf = 0;
				try {
					lenbuf = in.read(buffer);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (lenbuf <= 0)
					return false;
			}
			return true;
		}

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

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

		private void skip() {
			while (hasNextByte() && isSpaceChar(buffer[curbuf]))
				curbuf++;
		}

		public boolean hasNext() {
			skip();
			return hasNextByte();
		}

		public String next() {
			if (!hasNext())
				throw new NoSuchElementException();
			StringBuilder sb = new StringBuilder();
			int b = readByte();
			while (!isSpaceChar(b)) {
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		public int nextInt() {
			if (!hasNext())
				throw new NoSuchElementException();
			int c = readByte();
			while (isSpaceChar(c))
				c = readByte();
			boolean minus = false;
			if (c == '-') {
				minus = true;
				c = readByte();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res = res * 10 + c - '0';
				c = readByte();
			} while (!isSpaceChar(c));
			return (minus) ? -res : res;
		}

		public long nextLong() {
			if (!hasNext())
				throw new NoSuchElementException();
			int c = readByte();
			while (isSpaceChar(c))
				c = readByte();
			boolean minus = false;
			if (c == '-') {
				minus = true;
				c = readByte();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res = res * 10 + c - '0';
				c = readByte();
			} while (!isSpaceChar(c));
			return (minus) ? -res : res;
		}

		public double nextDouble() {
			return Double.parseDouble(next());
		}

		public int[] nextIntArray(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = nextInt();
			return a;
		}

		public long[] nextLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++)
				a[i] = nextLong();
			return a;
		}

		public char[][] nextCharMap(int n, int m) {
			char[][] map = new char[n][m];
			for (int i = 0; i < n; i++)
				map[i] = next().toCharArray();
			return map;
		}
	}

	static void tr(Object... o) {
		if (debug)
			out.println(Arrays.deepToString(o));
	}
}


Measured memory_bytes: 42016