#include 
#include 
using namespace std;
const int maxn = 1e5 + 10;
vector graph[maxn];
int color[maxn];
bool dfs(int node) {
    color[node] = 1;
    
    for(int i = 0; i < (int) graph[node].size(); i++) {
        int neighbour = graph[node][i];
        if(color[neighbour] == 1) {
            return true;
        }
        if(color[neighbour] == 0 and dfs(neighbour)) {
            return true;
        }
    }
    color[node] = 2;
    return false;
}
int main() {
    int n, m;
    cin >> n >> m;
    
    for(int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        graph[a].push_back(b);
    }
    for(int i = 0; i < n; i++) {
        color[i] = 0;
    }
    for(int i = 0; i < n; i++) {
        if(color[i] == 0) {
            if(dfs(i)) {
                cout << "cycle" << endl;
                return 0;
            }
        }
    }
    cout << "no cycle" << endl;
    return 0;
}