// #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<int, int> 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 = 30;
int64 dp[N][M][2];
string s[N][2];
int64 c[N];
int 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;
}

int64 solve(int k, int suf, int u) {
  int len = s[k][u].size();
  if (ispalin(s[k][u], len - suf, len)) return 0;
  int64& ret = dp[k][suf][u];
  if (ret >= 0) return ret;
  ret = INF;
  int v = 1 - u;
  for (int i = 0; i < n; ++i) {
    if (s[i][v].size() <= suf) {
      if (s[i][v] == s[k][u].substr(len - suf, s[i][v].size())) {
        ret = min(ret, c[i] + solve(k, suf - s[i][v].size(), u));
      }
    } else {
      if (s[k][u].substr(len - suf) == s[i][v].substr(0, suf)) {
        ret = min(ret, c[i] + solve(i, s[i][v].size() - suf, v));
      }
    }
  }
  return ret;
}

int main() {
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> s[i][0] >> c[i];
    s[i][1] = s[i][0];
    reverse(s[i][1].begin(), s[i][1].end());
  }
  int64 best = INF;
  memset(dp, 255, sizeof(dp));
  for (int i = 0; i < n; ++i) {
    int64 cur = c[i] + solve(i, s[i][0].size(), 0);
    trace(i, cur);
    best = min(best, cur);
  }
  if (best == INF) best = -1;
  cout << best << endl;
  return 0;
}


Measured memory_bytes: 3148