#include 
#include 
using namespace std;
int n, m;
vector graph[1005];
bool visited[1005], dfs_visited[1005];

bool dfs(int node) {
    visited[node] = true;
    dfs_visited[node] = true;
    
    for(int i = 0; i < graph[node].size(); i++) {
        int sosed = graph[node][i];
        if(!visited[sosed]) {
            if(dfs(sosed)) {
                return true;
            }
        }
        else if(dfs_visited[sosed]) {
            return true;
        }
    }
    dfs_visited[node] = false;
    return false;
}
int main() {
    cin >> n >> m;
    memset(visited, false, sizeof visited);
    memset(dfs_visited, false, sizeof dfs_visited);
    for(int i = 0; i < m; i++) {
        int a,b;
        cin >> a >> b;
        graph[a].push_back(b);
    }
    for(int i = 0; i < n; i++) {
        if(!visited[i] and dfs(i)) {
            cout << "DA" << endl;
            return 0;
        }
    }
    cout << "NE" << endl;
    return 0;
}