// #define LOCAL
#define _USE_MATH_DEFINES
#include <array>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <vector>
#include <queue>
#include <stack>
#include <list>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>
#include <complex>
#include <cmath>
#include <numeric>
#include <bitset>
#include <functional>
#include <random>
#include <ctime>

using namespace std;

template <typename A, typename B>
ostream& operator <<(ostream& out, const pair<A, B>& a) {
  out << "(" << a.first << "," << a.second << ")";
  return out;
}
template <typename T, size_t N>
ostream& operator <<(ostream& out, const array<T, N>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T>
ostream& operator <<(ostream& out, const vector<T>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T, class Cmp>
ostream& operator <<(ostream& out, const set<T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "}";
  return out;
}
template <typename U, typename T, class Cmp>
ostream& operator <<(ostream& out, const map<U, T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& p : a) { out << (first ? "" : ", "); out << p.first << ":" << p.second; first = 0;} out << "}";
  return out;
}
#ifdef LOCAL
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
#else
#define trace(...) 42
#endif
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << ": " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << ": " << arg1 << " |";
  __f(comma + 1, args...);
}

typedef long long int64;
typedef pair<int64, int64> ii;
#define SZ(x) (int)((x).size())
const int64 INF = 1LL << 60;
const int MOD = 1e9 + 7;
mt19937 mrand(random_device{}());
int rnd(int x) { return mrand() % x; }

struct fast_ios {
  fast_ios() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
  };
} fast_ios_;

const int N = 50;
const int M = 60;
int64 dp[N][M];
string s[N], t[N];
int64 c[N];

bool ispalin(const string& s, int L, int R) {
  for (int i = L, j = R - 1; i < j; ++i, --j) {
    if (s[i] != s[j]) return false;
  }
  return true;
}

vector<ii> a[N * M];

int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> s[i] >> c[i];
    t[i] = s[i];
    reverse(t[i].begin(), t[i].end());
  }

  for (int i = 0; i < n; ++i) {
    int len = SZ(s[i]);
    for (int k = 0; k <= len; ++k) {
      int v = i * M + k;
      for (int j = 0; j < n; ++j) {
        if (SZ(t[j]) < k) {
          if (t[j] == s[i].substr(len - k, SZ(t[j]))) {
            int u = i * M + (k - SZ(t[j]));
            a[u].push_back({v, c[j]});
          }
        } else {
          if (s[i].substr(len - k) == t[j].substr(0, k)) {
            int u = j * M + (SZ(t[j]) - k) + M / 2;
            a[u].push_back({v, c[j]});
          }
        }
      }
    }
    for (int k = 0; k <= len; ++k) {
      int v = i * M + k + M / 2;
      for (int j = 0; j < n; ++j) {
        if (SZ(s[j]) < k) {
          if (s[j] == t[i].substr(len - k, SZ(s[j]))) {
            int u = i * M + (k - SZ(s[j])) + M / 2;
            a[u].push_back({v, c[j]});
          }
        } else {
          if (t[i].substr(len - k) == s[j].substr(0, k)) {
            int u = j * M + (SZ(s[j]) - k);
            a[u].push_back({v, c[j]});
          }
        }
      }
    }
  }
  vector<int64> d(n * M, INF);
  priority_queue<ii, vector<ii>, greater<ii>> Q;
  for (int i = 0; i < n; ++i) {
    int len = s[i].size();
    for (int k = 0; k <= len; ++k) {
      if (ispalin(s[i], len - k, len)) {
        int u = i * M + k;
        d[u] = 0;
        Q.push({d[u], u});
        // trace("zero", u, i, k);
      }
      if (ispalin(t[i], len - k, len)) {
        int u = i * M + k + M / 2;
        d[u] = 0;
        Q.push({d[u], u});
      }
    }
  }
  while (!Q.empty()) {
    auto [dd, u] = Q.top();
    Q.pop();
    if (dd != d[u]) continue;
    for (auto& [v, w] : a[u]) {
      if (d[v] > d[u] + w) {
        d[v] = d[u] + w;
        Q.push({d[v], v});
      }
    }
  }
  int64 best = INF;
  for (int i = 0; i < n; ++i) {
    int u = i * M + SZ(s[i]);
    trace(i, u, d[u], c[i]);
    best = min(best, d[u] + c[i]);
    u = i * M + SZ(s[i]) + M / 2;
    best = min(best, d[u] + c[i]);
  }
  if (best == INF) best = -1;
  cout << best << endl;
  return 0;
}


Measured memory_bytes: 3392