#include <iostream>
#include <cstdio>
#include <algorithm>
#include <bits/stdc++.h>
#define ALL(x) (x).begin(), (x).end()
#define sz(a) int(a.size())
#define rep(i,x,n) for(int i=x;i<n;i++)
#define repd(i,x,n) for(int i=x;i<=n;i++)
#define pii pair<int,int>
#define pll pair<long long ,long long>
#define gbtb ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define MS0(X) memset((X), 0, sizeof((X)))
#define MSC0(X) memset((X), '\0', sizeof((X)))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define eps 1e-6
#define chu(x)  if(DEBUG_Switch) cout<<"["<<#x<<" "<<(x)<<"]"<<endl
#define du3(a,b,c) scanf("%d %d %d",&(a),&(b),&(c))
#define du2(a,b) scanf("%d %d",&(a),&(b))
#define du1(a) scanf("%d",&(a));
using namespace std;
typedef long long ll;
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
ll lcm(ll a, ll b) {return a / gcd(a, b) * b;}
ll powmod(ll a, ll b, ll MOD) { if (a == 0ll) {return 0ll;} a %= MOD; ll ans = 1; while (b) {if (b & 1) {ans = ans * a % MOD;} a = a * a % MOD; b >>= 1;} return ans;}
ll poww(ll a, ll b) { if (a == 0ll) {return 0ll;} ll ans = 1; while (b) {if (b & 1) {ans = ans * a ;} a = a * a ; b >>= 1;} return ans;}
void Pv(const vector<int> &V) {int Len = sz(V); for (int i = 0; i < Len; ++i) {printf("%d", V[i] ); if (i != Len - 1) {printf(" ");} else {printf("\n");}}}
void Pvl(const vector<ll> &V) {int Len = sz(V); for (int i = 0; i < Len; ++i) {printf("%lld", V[i] ); if (i != Len - 1) {printf(" ");} else {printf("\n");}}}
inline long long readll() {long long tmp = 0, fh = 1; char c = getchar(); while (c < '0' || c > '9') {if (c == '-') fh = -1; c = getchar();} while (c >= '0' && c <= '9') tmp = tmp * 10 + c - 48, c = getchar(); return tmp * fh;}
inline int readint() {int tmp = 0, fh = 1; char c = getchar(); while (c < '0' || c > '9') {if (c == '-') fh = -1; c = getchar();} while (c >= '0' && c <= '9') tmp = tmp * 10 + c - 48, c = getchar(); return tmp * fh;}
void pvarr_int(int *arr, int n, int strat = 1) {if (strat == 0) {n--;} repd(i, strat, n) {printf("%d%c", arr[i], i == n ? '\n' : ' ');}}
void pvarr_LL(ll *arr, int n, int strat = 1) {if (strat == 0) {n--;} repd(i, strat, n) {printf("%lld%c", arr[i], i == n ? '\n' : ' ');}}
const int maxn = 1000010;
const ll inf = 1e18;
/*** TEMPLATE CODE * * STARTS HERE ***/
#define DEBUG_Switch 0
int n;
string a[55];
ll c[55];
map<string, int> sid;
int ispal[maxn];
bool check(string str)
{
    string temp = str;
    reverse(ALL(temp));
    return temp == str;
}
ll dis[2][maxn];
struct Date
{
    ll cost;
    int dir;
    int id;
    Date() {}
    Date(ll cc, int dd, int ii)
    {
        cost = cc;
        dir = dd;
        id = ii;
    }
    bool operator < (const Date & b) const
    {
        return cost > b.cost;
    }
};
priority_queue<Date> q;
int main()
{
#if DEBUG_Switch
    freopen("C:\\code\\input.txt", "r", stdin);
#endif
    //freopen("C:\\code\\output.txt","w",stdout);
    cin >> n;
    repd(i, 1, n)
    {
        cin >> a[i] >> c[i];
    }
    ll ans = inf;
    repd(i, 1, n)
    {
        string temp = a[i];
        reverse(ALL(temp));
        if (temp == a[i])
        {
            ans = min(ans, c[i]);
        }
        temp = "";
        int m = sz(a[i]);
        repd(j, 0, m - 1)
        {
            temp.push_back(a[i][j]);
            if (sid.count(temp) == 0)
            {
                sid[temp] = sz(sid);
            }
        }
        temp = "";
        for (int j = m - 1; j >= 0; --j)
        {
            temp = a[i][j] + temp;
            if (sid.count(temp) == 0)
            {
                sid[temp] = sz(sid);
            }
        }
    }
    std::vector<string> v(sz(sid) + 10);
    for (auto s : sid)
    {
        ispal[s.se] = check(s.fi);
        dis[0][s.se] = dis[1][s.se] = inf;
        v[s.se] = s.fi;
    }
    repd(i, 1, n)
    {
        int id = sid[a[i]];
        dis[0][id] = dis[1][id] = c[i];
        q.push(Date(c[i], 0, id));
        q.push(Date(c[i], 1, id));
    }
    while (!q.empty())
    {
        Date temp = q.top();
        q.pop();
        if (dis[temp.dir][temp.id] < temp.cost)
            continue;
        repd(i, 1, n)
        {
            string left = v[temp.id];
            string right = a[i];
            if (temp.dir)
                swap(left, right);
            int pos = 0;
            while (pos < min(sz(left), sz(right)))
            {
                if (left[pos] == right[sz(right) - 1 - pos])
                {
                    pos++;
                } else
                {
                    break;
                }
            }
            if (pos < min(sz(left), sz(right)))
                continue;
            ll nd = temp.cost + c[i];
            if (pos == sz(left) && pos == sz(right))
            {
                ans = min(ans, nd );
            } else if (pos == sz(left))
            {
                string rm = right.substr(0, sz(right) - pos);
                if (ispal[sid[rm]])
                {
                    ans = min(ans, nd);
                } else
                {
                    int nowid = sid[rm];
                    if (dis[1][nowid] > nd)
                    {
                        dis[1][nowid] = nd;
                        q.push(Date(nd, 1, nowid));
                    }
                }
            } else
            {
                string rm = left.substr(pos);
                if (ispal[sid[rm]])
                {
                    ans = min(ans, nd);
                } else
                {
                    int nowid = sid[rm];
                    if (dis[0][nowid] > nd)
                    {
                        dis[0][nowid] = nd;
                        q.push(Date(nd, 0, nowid));
                    }
                }
            }
        }
    }
    if (ans == inf)
    {
        cout << -1 << endl;
    } else
    {
        cout << ans << endl;
    }
    return 0;

}




Measured memory_bytes: 3916