#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using V = vector<int>;
using Vll = vector<ll>;
using Vld = vector<ld>;
using Vbo = vector<bool>;
using VV = vector<V>;
using VVll = vector<Vll>;
using VVld = vector<Vld>;
using VVbo = vector<Vbo>;
using VVV = vector<VV>;
using VVVll = vector<VVll>;
using P = pair<int, int>;
using Pll = pair<ll, ll>;
using Pld = pair<ld, ld>;
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)
#define all(a) (a).begin(), (a).end()
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
template<typename T> inline int sz(T &x) { return x.size(); }
template<typename T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; }
template<typename T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; }
template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p) { is >> p.first >> p.second; return is; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p) { os << '(' << p.first << ", " << p.second << ')'; return os; }
template<typename T> istream &operator>>(istream &is, vector<T> &v) { for (auto &e : v) is >> e; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
template<typename T> inline int count_between(vector<T> &a, T l, T r) { return lower_bound(all(a), r) - lower_bound(all(a), l); } // [l, r)
inline int fLog2(const int x) { assert(x > 0); return 31-__builtin_clz(x); } // floor(log2(x))
inline int fLog2(const ll x) { assert(x > 0); return 63-__builtin_clzll(x); }
inline int cLog2(const int x) { assert(x > 0); return (x == 1) ? 0 : 32-__builtin_clz(x-1); } // ceil(log2(x))
inline int cLog2(const ll x) { assert(x > 0); return (x == 1) ? 0 : 64-__builtin_clzll(x-1); }
inline int popcount(const int x) { return __builtin_popcount(x); }
inline int popcount(const ll x) { return __builtin_popcountll(x); }
void fail() { cout << -1 << '\n'; exit(0); }
// const int INF  = 1<<30;
const ll INFll = 1ll<<62;
// const ld EPS   = 1e-10;
// const ld PI    = acos(-1.0);
// const int MOD  = int(1e9)+7;
// const int MOD  = 998244353;


template<typename T>
struct edge {
  int v; T w;
  edge(int v, T w) : v(v), w(w) {}
};
template<typename T>
using Graph = vector<vector<edge<T>>>;


string rev(string s) {
  reverse(all(s));
  return s;
}


map<string, int> idS[2];
vector<string> s[2];


int main() {
  int n; cin >> n;
  V c(n);
  rep(i, n) {
    string x;
    cin >> x >> c[i];
    s[0].push_back(x);
    s[1].push_back(rev(x));
  }

  const int M = 21;
  auto nid = [&] (int i, int j, int r) {
    return M*i + j + n*M*r;
  };

  int nv = n*M*2;
  Graph<ll> G(nv);

  rep(r, 2) rep(i, n) rep2(j, 1, sz(s[r][i])+1) rep(k, n) {
    auto t1 = rev(s[r][i].substr(0, j));
    auto t2 = s[r][k];

    int l = sz(t2);
    int mn = min(j, l);
    if (t1.substr(0, mn) != t2.substr(0, mn)) continue;
    
    int r2 = r;
    int i2 = i;
    int j2 = abs(j-l);
    if (j < l) r2 ^= 1, i2 = k;
    
    G[nid(i, j, r)].emplace_back(nid(i2, j2, r2), c[k]);
  }


  using T = ll;
  const auto INF_T = numeric_limits<T>::max();
  vector<T> dist(nv, INF_T);
  using PTi = pair<T, int>;
  priority_queue<PTi, vector<PTi>, greater<PTi>> pq;

  rep(i, n) {
    int x = nid(i, sz(s[0][i]), 0);
    dist[x] = c[i];
    pq.emplace(dist[x], x);
  }
  
  while (!pq.empty()) {
    auto [d, u] = pq.top(); pq.pop();
    if (dist[u] < d) continue;
    for (auto &[v, w] : G[u]) {
      if (chmin(dist[v], d+w)) {
        pq.emplace(dist[v], v);
      }
    }
  }

  ll ans = INFll;
  rep(r, 2) rep(i, n) rep(j, sz(s[r][i])+1) {
    auto t = s[r][i].substr(0, j);
    if (t == rev(t)) {
      chmin(ans, dist[nid(i, j, r)]);
    }
  }

  cout << (ans == INFll ? -1 : ans) << '\n';
  return 0;
}


Measured memory_bytes: 3748