#include <bits/stdc++.h>

using namespace std;

#define int int64_t

const int inf = 2e18;

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int l, r, n;
    cin >> l >> r >> n;
    l--;
    vector<char> from(n);
    vector<string> to(n);
    for (int i = 0; i < n; i++) {
        cin >> from[i] >> to[i];
        from[i] -= 'a';
        for (int j = 0; j < to[i].size(); j++) {
            to[i][j] -= 'a';
        }
    }
    vector<vector<int>> sz(n + 1, vector<int>(26, 1));
    for (int i = n - 1; i >= 0; i--) {
        sz[i] = sz[i + 1];
        sz[i][from[i]] = 0;
        for (char c: to[i]) {
            sz[i][from[i]] += sz[i + 1][c];
            sz[i][from[i]] = min(sz[i][from[i]], inf);
        }
    }
    vector<int> fr(26);
    string s(1, 0);
    for (int i = 0; i < n; i++) {
        vector<int> new_fr(26);
        for (int j = 0; j < 26; j++) {
            if (j != from[i]) {
                new_fr[j] += fr[j];
            } else {
                for (char c: to[i]) {
                    new_fr[c] += fr[j];
                }
            }
        }
        fr = new_fr;
        string new_s;
        for (char c: s) {
            if (c != from[i]) {
                new_s.push_back(c);
            } else {
                for (char c2: to[i]) {
                    new_s.push_back(c2);
                }
            }
        }
        int fin_sz = 0;
        for (int j = 0; j < 26; j++) {
            fin_sz += fr[j] * sz[i + 1][j];
        }
        s = "";
        for (char c: new_s) {
            fin_sz += sz[i + 1][c];
            if (fin_sz <= l) {
                fr[c]++;
                continue;
            }
            s.push_back(c);
            if (fin_sz >= r) {
                break;
            }
        }
    }
    for (int i = 0; i < s.size(); i++) {
        s[i] += 'a';
    }
    cout << s << endl;
}