int main() {
#ifdef Debug
freopen("1572.in", "r", stdin);
#endif
int n;
char input[10];
while (scanf("%d", &n) == 1 && n) {
memset(G, 0, sizeof(G));
while (n--) {
scanf("%s", input);
for (int i = 0; i < 4; ++i) {
for (int j = 0; j < 4; ++j) {
if (i != j) {
connect(input[2*i], input[2*i+1], input[2*j], input[2*j+1]);
}
}
}
}
if (hasCircle()) {
printf("unbounded\n");
} else {
printf("bounded\n");
}
}
return 0;
}
bool hasCircle(vector<vector<int>>& graph, vector<bool>& inGraph, vector<bool>& visited, int current) {
visited[current] = true;
inGraph[current] = true;
for(auto adj : graph[current]) {
if(!visited[adj]) {
if(hasCircle(graph, inGraph, visited, adj)) return true;
} else if(inGraph[adj]) {
return true;
}
}
inGraph[current] = false;
return false;
}
bool canFinish(int numCourses, vector<pair<int, int>>& prerequisites) {
vector<vector<int>> graph(numCourses, vector<int>());
vector<bool> visited(numCourses, false);
vector<bool> inGraph(numCourses, false);
for(auto p : prerequisites) {
graph[p.first].push_back(p.second);
}
for(int i=0; i<numCourses; i++) {
if(!visited[i]) {
if(hasCircle(graph, inGraph, visited, i)) return false;
}
}
return true;
}
