//In the Name of God
//Ya Ali

#include <bits/stdc++.h>

#define err(A) //cout << #A << " = " << (A) << endl

using namespace std;

int n;
int p1[24], p2[24], c[24], g[24], h[24];
string ans = "z";

void check(int msk) {
    memset(g, -1, sizeof g);
    memset(h, 0, sizeof h);
    bool bad = false;
    for (int i = 0; i < n; i ++) if ((1 << i) & msk) { swap(p1[i], p2[i]); err(i); }

    for (int i = n; i --;) {
        h[i] = max(h[i], c[i]);

        if (p1[i] == -1) {
            continue;
        }

        // C[i]
        if (c[p1[i]] != c[i]) {
            if (g[p1[i]] != -1 and g[p1[i]] != c[i]) {
                bad = true;
                break;
            }
            g[p1[i]] = c[i];
        }

        // G[i]
        if (g[i] != -1) {
            if (c[p2[i]] != g[i]) {
                if (g[p2[i]] != -1 and g[p2[i]] != g[i]) {
                    bad = true;
                    break;
                }
                g[p2[i]] = g[i];
            }
        } else if (h[i]) {
            h[p2[i]] = max(h[p2[i]], h[i]);
        }
    }

    string tmp;

    for (int i = 0; i < n; i ++) {
        if (p2[i] == -1) {
            if (g[i] == -1) {
                g[i] = h[i];
            }
        } else {
            if (g[i] == -1) {
                if (c[p2[i]] >= h[i])
                    g[i] = c[p2[i]];
                else
                    g[i] = g[p2[i]];
            }
        }

        if (g[i] < h[i]) {
            bad = true;
            break;
        }

        tmp += char('a' + c[i]);
        tmp += char('a' + g[i]);
        tmp += '\n';
    }

    for (int i = 0; i < n; i ++) if ((1 << i) & msk) swap(p1[i], p2[i]);
    if (!bad)
        ans = min(ans, tmp);
}

int32_t main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> p1[i] >> p2[i];
        p1[i]--;
        p2[i]--;
        char cc;
        cin >> cc;
        c[i] = cc - 'a';

    }

//    check(24);
    for (int msk = 0; msk < (1 << n); msk ++)
        check(msk);

    if (ans == "z")
        cout << -1 << endl;
    else
        cout << ans;

    return 0;
}