#include <algorithm>
#include <bitset>
#include <climits>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

#define MOD 1000000007
#define MOD2 998244353
#define int long long
#define double long double
#define EPS 1e-9
//#define PI 3.14159265358979

#define rep(i, n) for (int i = 0; i < (int)(n); i++)

using namespace std;

template < typename T >
ostream &operator<<(ostream &os, const vector< T > &A) {
	for (int i = 0; i < A.size(); i++)
		os << A[i] << " ";
	os << endl;
	return os;
}
template <>
ostream &operator<<(ostream &os, const vector< vector< int > > &A) {
	int N = A.size();
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < A[i].size(); j++)
			os << A[i][j] << " ";
		os << endl;
	}
	return os;
}

typedef pair< int, int > pii;
typedef long long ll;

struct edge {
	int from, to, d, c;
	edge(int _from = 0, int _to = 0, int _d = 0, int _c = 0) {
		from = _from;
		to = _to;
		d = _d;
		c = _c;
	}
	bool operator<(const edge &rhs) const {
		return (d == rhs.d) ? (c < rhs.c) : (d < rhs.d);
	}
};
struct aabb {
	int x1, y1, x2, y2;
	aabb(int x1, int y1, int x2, int y2) : x1(x1), y1(y1), x2(x2), y2(y2) {}
};

typedef vector< edge > edges;
typedef vector< edges > graph;
struct flow {
	int to, cap, rev, cost;
	flow(int to = 0, int cap = 0, int rev = 0, int cost = 0) : to(to), cap(cap), rev(rev), cost(cost) {}
};
typedef vector< vector< flow > > flows;

const int di[4] = {0, -1, 0, 1};
const int dj[4] = {-1, 0, 1, 0};
const int ci[5] = {0, 0, -1, 0, 1};
const int cj[5] = {0, -1, 0, 1, 0};
const ll LINF = LLONG_MAX / 2;
const int INF = INT_MAX / 2;
const double PI = acos(-1);

int pow2(int n) { return 1LL << n; }
template < typename T, typename U >
bool chmin(T &x, const U &y) {
	if (x > y) {
		x = y;
		return true;
	}
	return false;
}
template < typename T, typename U >
bool chmax(T &x, const U &y) {
	if (x < y) {
		x = y;
		return true;
	}
	return false;
}

struct initializer {
	initializer() {
		cout << fixed << setprecision(20);
	}
};
initializer _____;
vector< int > dijkstra(graph &G, int s) {
	///stat must have "<"&">"
	///init d=vector<stat>
	vector< int > d(G.size(), LINF);
	d[s] = 0;
	//init q=p-queue<pair<stat,index> >
	priority_queue< pii, vector< pii >, greater< pii > > q;
	q.push(pii(0, s));

	while (!q.empty()) {
		pii p = q.top();
		q.pop();
		if (d[p.second] < p.first)
			continue;
		for (int i = 0; i < G[p.second].size(); i++) {
			edge e = G[p.second][i];
			if (p.first + e.d < d[e.to]) {
				d[e.to] = p.first + e.d;
				q.push(pii(d[e.to], e.to));
			}
		}
	}
	return d;
}
int N, M, K, T, Q, H, W;
signed main() {
	cin >> N;
	vector< string > S(N);
	vector< int > C(N);
	rep(i, N) cin >> S[i] >> C[i];
	set< pair< int, string > > s;
	rep(i, N) {
		string T = S[i];
		M = T.size();
		rep(j, M) {
			s.emplace(1, T.substr(0, j + 1));
			s.emplace(0, T.substr(M - 1 - j, j + 1));
		}
	}
	vector< pair< int, string > > A;
	A.emplace_back(0, (string) "");
	for (auto p : s)
		A.push_back(p);
	A.emplace_back(1, (string) "");
	K = A.size();
	vector< int > p(K, 1);
	sort(A.begin(), A.end());
	rep(i, K) {
		string T = A[i].second;
		rep(j, A[i].second.size() / 2) {
			if (T[j] != T[T.size() - 1 - j])
				p[i] = 0;
		}
	}
	graph G(K);
	rep(i, K) {
		rep(j, N) {
			auto &p = A[i];
			string T = p.second;
			if (T == "") {
				if (p.first == 0) {
					edge e;
					e.from = i;
					e.d = C[j];
					e.to = lower_bound(A.begin(), A.end(), make_pair(0LL, S[j])) - A.begin();
					G[i].push_back(e);
					e.to = lower_bound(A.begin(), A.end(), make_pair(1LL, S[j])) - A.begin();
					G[i].push_back(e);
				}
			} else {
				if (p.first == 0) {
					int f = 1;
					rep(k, min(T.size(), S[j].size())) {
						if (T[k] != S[j][S[j].size() - 1 - k])
							f = 0;
					}
					if (f) {
						if (T.size() == S[j].size()) {
							edge e;
							e.from = i;
							e.d = C[j];
							e.to = lower_bound(A.begin(), A.end(), make_pair(1LL, (string) "")) - A.begin();
							G[i].push_back(e);
						} else if (T.size() < S[j].size()) {
							edge e;
							e.from = i;
							e.d = C[j];
							e.to = lower_bound(A.begin(), A.end(), make_pair(1LL, S[j].substr(0, S[j].size() - T.size()))) - A.begin();
							G[i].push_back(e);
						} else {
							edge e;
							e.from = i;
							e.d = C[j];
							e.to = lower_bound(A.begin(), A.end(), make_pair(0LL, T.substr(S[j].size(), T.size() - S[j].size()))) - A.begin();
							G[i].push_back(e);
						}
					}
				} else {
					int f = 1;
					rep(k, min(T.size(), S[j].size())) {
						if (T[T.size() - 1 - k] != S[j][k])
							f = 0;
					}
					if (f) {
						if (T.size() == S[j].size()) {
							edge e;
							e.from = i;
							e.d = C[j];
							e.to = lower_bound(A.begin(), A.end(), make_pair(1LL, (string) "")) - A.begin();
							G[i].push_back(e);
						} else if (T.size() < S[j].size()) {
							edge e;
							e.from = i;
							e.d = C[j];
							e.to = lower_bound(A.begin(), A.end(), make_pair(0LL, S[j].substr(T.size(), S[j].size() - T.size()))) - A.begin();
							G[i].push_back(e);
						} else {
							edge e;
							e.from = i;
							e.d = C[j];
							e.to = lower_bound(A.begin(), A.end(), make_pair(1LL, T.substr(0, T.size() - S[j].size()))) - A.begin();
							G[i].push_back(e);
						}
					}
				}
			}
		}
	}
	int start = lower_bound(A.begin(), A.end(), make_pair(0LL, (string) "")) - A.begin();
	vector< int > d = dijkstra(G, start);
	int ans = LINF;
	rep(i, K) if (p[i] && i != start) chmin(ans, d[i]);
	if (ans == LINF)
		ans = -1;
	cout << ans << endl;
	return 0;
}

Measured memory_bytes: 3972