// EXPECTED RESULT: CORRECT
//

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <set>
#include <string>
#include <vector>
using namespace std;

int main() {

	int shops;
	int total_inventory;

	cin >> shops;
	cin >> total_inventory;

	vector<set<string>> shop_items(shops, set<string>());

	for(int i = 0; i < total_inventory; i++) {
		int shop;
		string name;
		cin >> shop >> name;

		shop_items[shop].insert(name);
	}

	int total_items;
	cin >> total_items;

	vector<string> items;

	for(int i = 0; i < total_items; i++) {
		string item;
		cin >> item;
		items.push_back(item);
	}

	int cur_shop     = 0;
	int cur_item_pos = 0;
	bool ambiguous   = false;
	while(true) {

		if(cur_shop >= shops) { break; }

		if(cur_item_pos >= total_items) {
			while(cur_shop < shops) {
				string cur_item = items[cur_item_pos - 1];
				cerr << "item: " << cur_item << " shop: " << cur_shop << endl;
				if(shop_items[cur_shop].find(cur_item) != shop_items[cur_shop].end()) {
					ambiguous = true;
				}
				cur_shop++;
			}

			break;
		}

		string cur_item  = items[cur_item_pos];
		string prev_item = cur_item_pos == 0 ? "" : items[cur_item_pos - 1];

		if(shop_items[cur_shop].find(prev_item) != shop_items[cur_shop].end()) { ambiguous = true; }

		if(shop_items[cur_shop].find(cur_item) != shop_items[cur_shop].end()) {

			// shop_items[cur_shop].erase(cur_item);

			// go to next letter
			cur_item_pos++;
		} else {
			cur_shop++;
		}
	}

	if(cur_item_pos == total_items) {
		if(ambiguous) {
			cout << "ambiguous" << endl;
		} else {
			cout << "unique" << endl;
		}
	} else {
		cout << "impossible" << endl;
	}

	return 0;
}