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//
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//       ?77WMMMYB""!                                                                        _7"WWMMMY"7=     

// need
#include <iostream>
#include <algorithm>
// data structure
#include <bitset>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#include <complex>
//#include <deque>
#include <valarray>
#include <unordered_map>
#include <unordered_set>
#include <array>
// etc
#include <cassert>
#include <cmath>
#include <functional>
#include <iomanip>
#include <chrono>
#include <random>
#include <numeric>
#include <fstream>

auto& scan_in = std::cin;

// input
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
#define VAR(type, ...)type __VA_ARGS__;MACRO_VAR_Scan(__VA_ARGS__);
template<typename T> void MACRO_VAR_Scan(T& t) { scan_in >> t; }
template<typename First, typename...Rest>void MACRO_VAR_Scan(First& first, Rest& ...rest) { scan_in >> first; MACRO_VAR_Scan(rest...); }
#define VEC_ROW(type, n, ...)std::vector<type> __VA_ARGS__;MACRO_VEC_ROW_Init(n, __VA_ARGS__); for(int w_=0; w_<n; ++w_){MACRO_VEC_ROW_Scan(w_, __VA_ARGS__);}
template<typename T> void MACRO_VEC_ROW_Init(int n, T& t) { t.resize(n); }
template<typename First, typename...Rest>void MACRO_VEC_ROW_Init(int n, First& first, Rest& ...rest) { first.resize(n); MACRO_VEC_ROW_Init(n, rest...); }
template<typename T> void MACRO_VEC_ROW_Scan(int p, T& t) { scan_in >> t[p]; }
template<typename First, typename...Rest>void MACRO_VEC_ROW_Scan(int p, First& first, Rest& ...rest) { scan_in >> first[p]; MACRO_VEC_ROW_Scan(p, rest...); }
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)scan_in>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& R:c)for(auto& w:R)scan_in>>w;
// output
template<typename T>void MACRO_OUT(const T t) { std::cout << t; }
template<typename First, typename...Rest>void MACRO_OUT(const First first, const Rest...rest) { std::cout << first << " "; MACRO_OUT(rest...); }
#define OUT(...) MACRO_OUT(__VA_ARGS__);
#define FOUT(n, dist) std::cout<<std::fixed<<std::setprecision(n)<<(dist);
#define SOUT(n, c, dist) std::cout<<std::setw(n)<<std::setfill(c)<<(dist);
#define VOUT(v) for(size_t i = 0; i < v.size(); ++i) {OUT(v[i]);if(i+1<v.size()){SP}}
#define EOUT(...) do{ OUT(__VA_ARGS__)BR; exit(0); }while(0);
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define SPBR(w, n) std::cout<<(w + 1 == n ? '\n' : ' ');
#define ENDL std::cout<<std::endl;
#define FLUSH std::cout<<std::flush;
#define SHOW(dist) {std::cerr << #dist << "\t: " << (dist) << "\n";}
// utility
#define ALL(a) (a).begin(),(a).end()
#define FOR(w, a, n) for(int w=(a);w<(n);++w)
#define REP(w, n) FOR(w, 0, n)
#define RFOR(w, a, n) for(int w=(n)-1;w>=(a);--w)
#define RREP(w, n) RFOR(w, 0, n)
template<class S, class T, class U> bool IN(S a, T x, U b) { return a <= x && x < b; }
template<class T> inline T CHMAX(T& a, const T b) { return a = (a < b) ? b : a; }
template<class T> inline T CHMIN(T& a, const T b) { return a = (a > b) ? b : a; }
// test
template<class T> using V = std::vector<T>;
template<class T> using VV = V<V<T>>;

template<typename S, typename T>
std::ostream& operator<<(std::ostream& os, const std::pair<S, T>& p) {
	os << "(" << p.first << ", " << p.second << ")"; return os;
}
template<typename T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) {
	os << "{";
	for (size_t i = 0; i < v.size(); ++i) os << v[i] << ((i + 1 < v.size()) ? ", " : ""); os << "}";
	return os;
}
template<typename S, typename T>
std::ostream & operator<<(std::ostream & os, const std::map<S, T> & m) {
	os << "{";
	for (auto it = m.cbegin(); it != m.cend();) { os << it->first << ":" << it->second; ++it; os << (it == m.cend() ? "" : ", "); } os << "}";
	return os;
}
template<typename T>
std::ostream& operator<<(std::ostream & os, std::queue<T> q) {
	os << "<";
	while (!q.empty()) { os << q.front(); q.pop(); os << (q.empty() ? "<" : ", "); }
	return os;
}
template<typename T>
std::ostream& operator<<(std::ostream & os, std::stack<T> q) {
	os << ">";
	while (!q.empty()) { os << q.top(); q.pop(); os << (q.empty() ? "]" : ", "); }
	return os;
}
namespace std {
	template<typename S, typename T> class numeric_limits<pair<S, T>> {
	public:
		static constexpr pair<S, T> max() noexcept { return { numeric_limits<S>::max(), numeric_limits<T>::max() }; }
		static constexpr pair<S, T> lowest() noexcept { return { numeric_limits<S>::lowest(), numeric_limits<T>::lowest() }; }
	};
}

// type/const
using i64 = std::int_fast64_t;
using u64 = std::uint_fast64_t;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using PAIR = std::pair<i64, i64>;
using PAIRLL = std::pair<ll, ll>;
constexpr int INFINT = (1 << 30) - 1;                    // 1.07x10^ 9
constexpr int INFINT_LIM = (1LL << 31) - 1;              // 2.15x10^ 9
constexpr ll INFLL = 1LL << 60;                          // 1.15x10^18
constexpr ll INFLL_LIM = (1LL << 62) - 1 + (1LL << 62);  // 9.22x10^18
constexpr double EPS = 1e-6;
constexpr i64 MOD = 1000000007;
constexpr double PI = 3.141592653589793238462643383279;
template<class T, size_t N> void FILL(T(&a)[N], const T & val) { for (auto& x : a) x = val; }
template<class ARY, size_t N, size_t M, class T> void FILL(ARY(&a)[N][M], const T & val) { for (auto& b : a) FILL(b, val); }
template<class T> void FILL(std::vector<T> & a, const T & val) { for (auto& x : a) x = val; }
template<class ARY, class T> void FILL(std::vector<std::vector<ARY>> & a, const T & val) { for (auto& b : a) FILL(b, val); }
// ------------>8---------

struct HashData {
	int h1, h2;
	bool operator==(const HashData& rhs) const {
		return h1 == rhs.h1 && h2 == rhs.h2;
	}
	bool operator!=(const HashData& rhs) const { return !(*this == rhs); }
};
class RollingHash {
	template<int B, int M>
	class RollingHashPart {
	private:
		size_t len;
		std::vector<int> pow_b, hash;
	public:
		RollingHashPart() {}
		template<typename T>
		RollingHashPart(const T& s) : len(s.size()), pow_b(s.size() + 1), hash(s.size() + 1) {
			pow_b[0] = 1;
			hash[0] = 0;
			for (int i = 0; i < len; i++) {
				pow_b[i + 1] = (ll)pow_b[i] * B % M;
				hash[i + 1] = ((ll)hash[i] * B + s[i]) % M;
			}
		}
		// [l, r)
		int get(int l, int r) const {
			int res = (hash[r] - (ll)hash[l] * pow_b[r - l]) % M;
			if (res < 0) res += M;
			return res;
		}
	};
public:
	RollingHashPart<1033, 1000000007> rh1;
	RollingHashPart<6037, 999999937> rh2;

	RollingHash() {}
	template<typename T> RollingHash(const T & s) : rh1(s), rh2(s) {}
	// [l, r)
	HashData get(int l, int r) const {
		return HashData{ rh1.get(l, r), rh2.get(l, r) };
	}
	// [l1, r1), [l2, r2)
	int lcp(const RollingHash & rhs, int l1, int r1, int l2, int r2) const {
		int lb = 0, ub = std::min(r1 - l1, r2 - l2) + 1;
		while (ub - lb > 1) {
			int md = (lb + ub) >> 1;
			(get(l1, l1 + md) == rhs.get(l2, l2 + md) ? lb : ub) = md;
		}
		return lb;
	}
};

std::map<std::string, i64> dp[2];
int n;
std::string s[52];
i64 c[52];
RollingHash rh[52];

std::map<std::string, bool> isP;
bool isPalindromic(const std::string & s) {
	auto it = isP.find(s);
	if (it != isP.end()) return it->second;
	auto& res = isP[s];
	size_t sn = s.size();
	size_t n = sn / 2;
	for (size_t i = 0; i < n; ++i) {
		if (s[i] != s[sn - i - 1]) return res = false;
	}
	return res = true;
}

i64 rec(std::string x, int p) {
	if (dp[p].count(x)) return dp[p][x];
	auto& res = dp[p][x];
	dp[p][x] = INFLL;

	std::reverse(ALL(x));
	RollingHash r(x);
	REP(i, n) {
		if (p == 0) {
			if (x.size() < s[i].size()) {
				if (rh[i].get(s[i].size() - x.size(), s[i].size()) == r.get(0, x.size())) {
					std::string t(s[i].begin(), s[i].begin() + s[i].size() - x.size());
					if (isPalindromic(t)) CHMIN(res, c[i]);
					else CHMIN(res, rec(t, 1) + c[i]);
				}
			}
			else {
				if (rh[i].get(0, s[i].size()) == r.get(x.size() - s[i].size(), x.size())) {
					std::string t(x.begin(), x.begin() + x.size() - s[i].size());
					if (isPalindromic(t)) CHMIN(res, c[i]);
					else {
						std::reverse(ALL(t));
						CHMIN(res, rec(t, 0) + c[i]);
					}
				}
			}
		}
		else {
			if (x.size() < s[i].size()) {
				if (rh[i].get(0, x.size()) == r.get(0, x.size())) {
					std::string t(s[i].begin() + x.size(), s[i].end());
					if (isPalindromic(t)) CHMIN(res, c[i]);
					else CHMIN(res, rec(t, 0) + c[i]);
				}
			}
			else {
				if (rh[i].get(0, s[i].size()) == r.get(0, s[i].size())) {
					std::string t(x.begin() + s[i].size(), x.end());
					if (isPalindromic(t)) CHMIN(res, c[i]);
					else {
						std::reverse(ALL(t));
						CHMIN(res, rec(t, 1) + c[i]);
					}
				}
			}
		}
	}
	return res;
}

signed main() {
	INIT;

	std::cin >> n;
	REP(i, n) std::cin >> s[i] >> c[i];
	REP(i, n) rh[i] = RollingHash(s[i]);

	i64 ans = INFLL;
	REP(i, n) {
		if (isPalindromic(s[i])) CHMIN(ans, c[i]);
		else {
			CHMIN(ans, rec(s[i], 0) + c[i]);
		}
	}
	if (ans >= INFLL) ans = -1;
	OUT(ans)BR;

	return 0;
}

Measured memory_bytes: 3668