Problem:
Score : 700 points

Problem Statement

Limak can repeatedly remove one of the first two characters of a string,
for example abcxyx \rightarrow acxyx \rightarrow cxyx \rightarrow cyx.

You are given N different strings S_1, S_2, \ldots, S_N.
Among N \cdot (N-1) / 2 pairs (S_i, S_j),
in how many pairs could Limak obtain one string from the other?

Constraints

2 \leq N \leq 200\,000

S_i consists of lowercase English letters a-z.

S_i \neq S_j

1 \leq |S_i|

|S_1| + |S_2| + \ldots + |S_N| \leq 10^6

Input

Input is given from Standard Input in the following format.

N
S_1
S_2
\vdots
S_N

Output

Print the number of unordered pairs (S_i, S_j)
where i \neq j and Limak can obtain one string from the other.

Sample Input 1

3
abcxyx
cyx
abc

Sample Output 1

1

The only good pair is (abcxyx, cyx).

Sample Input 2

6
b
a
abc
c
d
ab

Sample Output 2

5

There are five good pairs: (b, abc), (a, abc), (abc, c), (b, ab), (a, ab).

Solution in Java (OpenJDK 11.0.6) (judge verdict: Memory Limit Exceeded)

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Arrays;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.io.Closeable;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) throws Exception {
        Thread thread = new Thread(null, new TaskAdapter(), "", 1 << 29);
        thread.start();
        thread.join();
    }

    static class TaskAdapter implements Runnable {
        @Override
        public void run() {
            InputStream inputStream = System.in;
            OutputStream outputStream = System.out;
            FastInput in = new FastInput(inputStream);
            FastOutput out = new FastOutput(outputStream);
            BFirstSecond solver = new BFirstSecond();
            solver.solve(1, in, out);
            out.close();
        }
    }

    static class BFirstSecond {
        public void solve(int testNumber, FastInput in, FastOutput out) {
            int n = in.readInt();
            byte[][] strings = new byte[n][];
            byte[] s = new byte[(int) 1e6];
            Node root = new Node();
            long ans = 0;
            for (int i = 0; i < n; i++) {
                int len = in.readString(s, 0);
                for (int j = 0; j < len; j++) {
                    s[j] -= 'a';
                }
                SequenceUtils.reverse(s, 0, len - 1);
                strings[i] = Arrays.copyOf(s, len);
            }

            Arrays.sort(strings, (a, b) -> Integer.compare(a.length, b.length));
            for (byte[] string : strings) {
                int len = string.length;
                int[] suf = new int[len];
                suf[len - 1] = 1 << string[len - 1];
                for (int j = len - 2; j >= 0; j--) {
                    suf[j] = suf[j + 1] | (1 << string[j]);
                }
                int contrib = root.count(string, suf, 0);
                ans += contrib;
                root.add(string, 0);
            }
            out.println(ans);
        }

    }

    static class FastInput {
        private final InputStream is;
        private byte[] buf = new byte[1 << 13];
        private int bufLen;
        private int bufOffset;
        private int next;

        public FastInput(InputStream is) {
            this.is = is;
        }

        private int read() {
            while (bufLen == bufOffset) {
                bufOffset = 0;
                try {
                    bufLen = is.read(buf);
                } catch (IOException e) {
                    bufLen = -1;
                }
                if (bufLen == -1) {
                    return -1;
                }
            }
            return buf[bufOffset++];
        }

        public void skipBlank() {
            while (next >= 0 && next <= 32) {
                next = read();
            }
        }

        public int readInt() {
            int sign = 1;

            skipBlank();
            if (next == '+' || next == '-') {
                sign = next == '+' ? 1 : -1;
                next = read();
            }

            int val = 0;
            if (sign == 1) {
                while (next >= '0' && next <= '9') {
                    val = val * 10 + next - '0';
                    next = read();
                }
            } else {
                while (next >= '0' && next <= '9') {
                    val = val * 10 - next + '0';
                    next = read();
                }
            }

            return val;
        }

        public int readString(byte[] data, int offset) {
            skipBlank();

            int originalOffset = offset;
            while (next > 32) {
                data[offset++] = (byte) next;
                next = read();
            }

            return offset - originalOffset;
        }

    }

    static class Node {
        static int charset = 'z' - 'a' + 1;
        Node[] next = new Node[charset];
        int cnt;

        public Node get(int i) {
            if (next[i] == null) {
                next[i] = new Node();
            }
            return next[i];
        }

        public int count(byte[] seq, int[] suf, int i) {
            if (i == seq.length) {
                return 0;
            }
            int ans = 0;
            for (int j = 0; j < charset; j++) {
                if (next[j] != null && Bits.get(suf[i], j) == 1) {
                    ans += next[j].cnt;
                }
            }
            if (next[seq[i]] != null) {
                ans += next[seq[i]].count(seq, suf, i + 1);
            }
            return ans;
        }

        public void add(byte[] seq, int i) {
            if (i == seq.length) {
                cnt++;
                return;
            }
            get(seq[i]).add(seq, i + 1);
        }

    }

    static class FastOutput implements AutoCloseable, Closeable, Appendable {
        private StringBuilder cache = new StringBuilder(10 << 20);
        private final Writer os;

        public FastOutput append(CharSequence csq) {
            cache.append(csq);
            return this;
        }

        public FastOutput append(CharSequence csq, int start, int end) {
            cache.append(csq, start, end);
            return this;
        }

        public FastOutput(Writer os) {
            this.os = os;
        }

        public FastOutput(OutputStream os) {
            this(new OutputStreamWriter(os));
        }

        public FastOutput append(char c) {
            cache.append(c);
            return this;
        }

        public FastOutput append(long c) {
            cache.append(c);
            return this;
        }

        public FastOutput println(long c) {
            return append(c).println();
        }

        public FastOutput println() {
            cache.append(System.lineSeparator());
            return this;
        }

        public FastOutput flush() {
            try {
                os.append(cache);
                os.flush();
                cache.setLength(0);
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
            return this;
        }

        public void close() {
            flush();
            try {
                os.close();
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }

        public String toString() {
            return cache.toString();
        }

    }

    static class Bits {
        private Bits() {
        }

        public static int get(int x, int i) {
            return (x >>> i) & 1;
        }

    }

    static class SequenceUtils {
        public static void swap(byte[] data, int i, int j) {
            byte tmp = data[i];
            data[i] = data[j];
            data[j] = tmp;
        }

        public static void reverse(byte[] data, int l, int r) {
            while (l < r) {
                swap(data, l, r);
                l++;
                r--;
            }
        }

    }
}