This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int,int> pi;
#define f first
#define s second
#define FAST ios_base::sync_with_stdio(0); cin.tie(0);
const int maxn = 1010;
int n,e;
int edge[maxn][maxn];
int flip[maxn];
int32_t main() {
	FAST
	cin >> n >> e;
	for (int i =0;i<e;i++) {
		int a,b; cin >> a >> b;
		edge[a][b] = edge[b][a] = 1;
	}
	
	for (int i =2; i<= n;i++) {
		if (!edge[1][i]) flip[i] = 1;
	}
	
	bool fail = false;
	
	for (int a = 1; a<= n;a++) {
		for (int b = 1; b <= n; b++) {
			if (a == b) continue;
			//cout << "a:" <<  a << " b:" << b << "\n";
			//cout << flip[a] << " " << flip[b] << " " << edge[a][b] << "\n";
			
			if (flip[a] and !flip[b] and edge[a][b]) fail = true;
			if (flip[b] and !flip[a] and edge[a][b]) fail = true;
			if (!flip[a] and !flip[b] and !edge[a][b]) fail = true;
			//cout << fail << "\n";
		}
	}
	
	
	memset(flip,0,sizeof flip);
	flip[1] = 1;
	for (int i =2; i<= n;i++) {
		if (edge[1][i]) flip[i] = 1;
	}
	
	for (int a = 1; a<= n;a++) {
		for (int b = 1; b <= n; b++) {
			if (a == b) continue;
			if (flip[a] and !flip[b] and edge[a][b]) fail = true;
			if (flip[b] and !flip[a] and edge[a][b]) fail = true;
			if (!flip[a] and !flip[b] and !edge[a][b]) fail = true;
		}
	}
	
	if (fail) cout << "NE";
	else cout << "DA";
	
}
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