#include <bits/stdc++.h>

#define pb push_back
#define mp make_pair
#define sz size
#define ll long long
#define ld long double
#define fs first
#define sc second
#define forn(i, f, t) for(int i = f; i < t; i++)
#define all(x) (x).begin(), (x).end()
#define ins insert

const int INF = 2147483647;
const int MOD = 1000000007;
const ll INF64 = 9223372036854775807;
const ld EPS = 1e-7;

using namespace std;


int main(){
    int n, m, k, t, ans = 0;
    string ph, s;
    vector<pair<int, string> > phs;
    cin >> m >> n;
    cin >> s;
    forn(i, 0, n){
        cin >> k >> t;
        cin >> ph;
        phs.pb(mp(t, ph));
    }
    sort(all(phs));
    string tmp = "";
    forn(i, 0, n){
        tmp = phs[i].sc + '#' + s;
        int pos = phs[i].sc.sz() + 1;
        for (; tmp[0] != '#'; tmp = tmp.substr(1, tmp.sz() - 1)){
            int l = tmp.sz();
            int p[l];
            p[0] = 0;
            forn(j, 1, l){
                int d = p[j - 1];
                while (tmp[d] != tmp[j] && d)
                    d = p[d - 1];
                p[j] = d + (tmp[d] == tmp[j]);
            }
            /*forn(j, 0, pos) cout << " ";
            forn(j, pos, l)
                cout << p[j];
            cout << "\n";*/
            forn(j, pos, l - 1)
                if (p[j + 1] == 0)
                    forn(z, j - p[j] + 1, j + 1)
                        tmp[z] = '0';
            if (p[l - 1] != 0)
                forn(z, l - p[l - 1], l)
                    tmp[z] = '0';
            // cout << tmp << " ";
            string tmp2 = tmp;
            tmp = "";
            int cur = 0;
            forn(j, 0, tmp2.sz())
                if (tmp2[j] != '0')
                    tmp += tmp2[j];
                else
                    cur++;
            ans += cur * phs[i].fs;
            pos--;
            // cout << tmp << "\n";
        }
        s = tmp.substr(tmp.find('#') + 1, tmp.sz() - tmp.find('#'));
    }
    cout << (tmp.find('#') != tmp.sz() - 1 ? -1 : ans) << "\n";
    return 0;
}