import java.io.*;
import java.util.*;

class Util {
  public static boolean isP(String s) {
    for (int i = 0; i < s.length() / 2; i++) {
      if (s.charAt(i) != s.charAt(s.length() - i - 1)) {
        return false;
      }
    }
    return true;
  }
}

class State {
  final String head;
  final String tail;

  State(String head, String tail) {
    this.head = head;
    this.tail = tail;
  }

  public boolean equals(Object object) {
    State state = (State) object;
    return this.head.equals(state.head) && this.tail.equals(state.tail);
  }

  public int hasCode() {
    return 13 * head.hashCode() + tail.hashCode();
  }

  public boolean isP() {
    return Util.isP(head) && Util.isP(tail);
  }
}

class Node implements Comparable<Node> {
  final State state;
  final long cost;

  Node(State state, long cost) {
    this.state = state;
    this.cost = cost;
  }

  public int compareTo(Node node) {
    return Long.compare(this.cost, node.cost);
  }
}

class Solver {
  final int n;
  final String[] ss;
  final long[] cs;

  Solver(int n, String[] ss, long[] cs) {
    this.n = n;
    this.ss = ss;
    this.cs = cs;
  }


  public long solve() {
    PriorityQueue<Node> queue = new PriorityQueue<>();
    HashSet<State> set = new HashSet<>();
    for (int i = 0; i < n; i++) {
      queue.add(new Node(new State(ss[i], ""), cs[i]));
    }
    while (!queue.isEmpty()) {
      Node node = queue.poll();
      State state = node.state;
      long cost = node.cost;
      if (set.contains(state)) {
        continue;
      }
      set.add(state);
      if (state.isP()) {
        return cost;
      }
      for (int i = 0; i < n; i++) {
        if (state.head.isEmpty()) {
          boolean canP = true;
          int minLength = Math.min(ss[i].length(), state.tail.length());
          for (int j = 0; j < minLength; j++) {
            if (ss[i].charAt(j) != state.tail.charAt(state.tail.length() - 1 - j)) {
              canP = false;
              break;
            }
          }
          if (canP) {
            State newState = new State(ss[i].substring(minLength), state.tail.substring(0, state.tail.length() - minLength));
            if (!set.contains(newState)) {
              queue.add(new Node(newState, cost + cs[i]));
            }
          }
        } else if (state.tail.isEmpty()) {
          boolean canP = true;
          String head = state.head;
          int minLength = Math.min(head.length(), ss[i].length());
          for (int j = 0; j < minLength; j++) {
            if (head.charAt(j) != ss[i].charAt(ss[i].length() - 1 - j)) {
              canP = false;
              break;
            }
          }
          if (canP) {
            State newState = new State(head.substring(minLength), ss[i].substring(0, ss[i].length() - minLength));
            if (!set.contains(newState)) {
              queue.add(new Node(newState, cost + cs[i]));
            }
          }
        }
      }
    }
    return -1;
  }
}

public class Main {
  private static void execute(ContestReader reader, ContestWriter out) {
    int n = reader.nextInt();
    String[] ss = new String[n];
    long[] cs = new long[n];
    for (int i = 0; i < n; i++) {
      ss[i] = reader.next();
      cs[i] = reader.nextLong();
    }
    out.println(new Solver(n, ss, cs).solve());
  }
  
  public static void main(String[] args) {
    ContestReader reader = new ContestReader(System.in);
    ContestWriter out = new ContestWriter(System.out);
    execute(reader, out);
    out.flush();
  }
}

class ContestWriter extends PrintWriter {
  ContestWriter(PrintStream printStream) {
    super(printStream);
  }

  public void printList(List<? extends Object> list) {
    for (Object object : list) {
      println(object);
    }
  }

  public void printListOneLine(List<? extends Object> list) {
    List<String> stringList = new ArrayList<>();
    for (Object object : list) {
      stringList.add(object.toString());
    }
    println(String.join(" ", stringList));
  }
}

class ContestReader {
  private static final int BUFFER_SIZE = 1024;
  
  private final InputStream stream;
  private final byte[] buffer;
  private int pointer;
  private int bufferLength;
  
  ContestReader(InputStream stream) {
    this.stream = stream;
    this.buffer = new byte[BUFFER_SIZE];
    this.pointer = 0;
    this.bufferLength = 0;
  }
  
  private boolean hasNextByte() {
    if (pointer < bufferLength) {
      return true;
    }
    
    pointer = 0;
    try {
      bufferLength = stream.read(buffer);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
    return bufferLength > 0;
  }
  
  private int readByte() {
    if (hasNextByte()) {
      return buffer[pointer++];
    } else {
      return -1;
    }
  }
  
  private static boolean isPrintableChar(int c) {
    return 33 <= c && c <= 126;
  }
  
  public boolean hasNext() {
    while (hasNextByte() && !isPrintableChar(buffer[pointer])) {
      pointer++;
    }
    return hasNextByte();
  }
  
  public String next() {
    if (!hasNext()) {
      throw new NoSuchElementException();
    }
    StringBuilder sb = new StringBuilder();
    while(true) {
      int b = readByte();
      if (!isPrintableChar(b)) {
        break;
      }
      sb.appendCodePoint(b);
    }
    return sb.toString();
  }
  
  public String nextLine() {
    if (!hasNext()) {
      throw new NoSuchElementException();
    }
    StringBuilder sb = new StringBuilder();
    while(true) {
      int b = readByte();
      if (!isPrintableChar(b) && b != 0x20) {
        break;
      }
      sb.appendCodePoint(b);
    }
    return sb.toString();
  }
  
  public char nextChar() {
    return next().charAt(0);
  }
  
  public int nextInt() {
    if (!hasNext()) {
      throw new NoSuchElementException();
    }
    
    int n = 0;
    boolean minus = false;
    
    {
      int b = readByte();
      if (b == '-') {
        minus = true;
      } else if ('0' <= b && b <= '9') {
        n = b - '0';
      } else {
        throw new NumberFormatException();
      }
    }
    
    while(true){
      int b = readByte();
      if ('0' <= b && b <= '9') {
        n *= 10;
        n += b - '0';
      } else if (b == -1 || !isPrintableChar(b)) {
        return minus ? -n : n;
      } else {
        throw new NumberFormatException();
      }
    }
  }
  
  public long nextLong() {
    if (!hasNext()) {
      throw new NoSuchElementException();
    }
    
    long n = 0;
    boolean minus = false;
    
    {
      int b = readByte();
      if (b == '-') {
        minus = true;
      } else if ('0' <= b && b <= '9') {
        n = b - '0';
      } else {
        throw new NumberFormatException();
      }
    }
    
    while(true){
      int b = readByte();
      if ('0' <= b && b <= '9') {
        n *= 10;
        n += b - '0';
      } else if (b == -1 || !isPrintableChar(b)) {
        return minus ? -n : n;
      } else {
        throw new NumberFormatException();
      }
    }
  }
  
  public double nextDouble() {
    return Double.parseDouble(next());
  }
  
  public String[] next(int n) {
    String[] array = new String[n];
    for (int i = 0; i < n; i++) {
      array[i] = next();
    }
    return array;
  }
  
  public String[] nextLine(int n) {
    String[] array = new String[n];
    for (int i = 0; i < n; i++) {
      array[i] = nextLine();
    }
    return array;
  }
  
  public char[] nextChar(int n) {
    char[] array = new char[n];
    for (int i = 0; i < n; i++) {
      array[i] = nextChar();
    }
    return array;
  }
  
  public int[] nextInt(int n) {
    int[] array = new int[n];
    for (int i = 0; i < n; i++) {
      array[i] = nextInt();
    }
    return array;
  }
  
  public long[] nextLong(int n) {
    long[] array = new long[n];
    for (int i = 0; i < n; i++) {
      array[i] = nextLong();
    }
    return array;
  }
  
  public double[] nextDouble(int n) {
    double[] array = new double[n];
    for (int i = 0; i < n; i++) {
      array[i] = nextDouble();
    }
    return array;
  }
  
  public char[] nextCharArray() {
    return next().toCharArray();
  }
  
  public String[][] next(int n, int m) {
    String[][] matrix = new String[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        matrix[i][j] = next();
      }
    }
    return matrix;
  }
  
  public int[][] nextInt(int n, int m) {
    int[][] matrix = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        matrix[i][j] = nextInt();
      }
    }
    return matrix;
  }
  
  public char[][] nextChar(int n, int m) {
    char[][] matrix = new char[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        matrix[i][j] = nextChar();
      }
    }
    return matrix;
  }
  
  public long[][] nextLong(int n, int m) {
    long[][] matrix = new long[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        matrix[i][j] = nextLong();
      }
    }
    return matrix;
  }
  
  public double[][] nextDouble(int n, int m) {
    double[][] matrix = new double[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        matrix[i][j] = nextDouble();
      }
    }
    return matrix;
  }
  
  public char[][] nextCharArray(int n) {
    char[][] matrix = new char[n][];
    for (int i = 0; i < n; i++) {
      matrix[i] = next().toCharArray();
    }
    return matrix;
  }
}

class MyAssert {
  public static void myAssert(boolean flag, String message) {
    if (!flag) {
      throw new RuntimeException(message);
    }
  }
 
  public static void myAssert(boolean flag) {
    myAssert(flag, "");
  }
}


Measured memory_bytes: 39192