#include #define F first #define S second #define X real() #define Y imag() using namespace std; typedef long long ll; typedef long double ld; struct LPSolver { const ld eps=1e-9; const ld inf=1e30; int m, n; vector N, B; vector > D; LPSolver(vector >& A, vector& b, vector& c) : m(b.size()), n(c.size()), N(n + 1), B(m), D(m + 2, vector(n + 2)) { for (int i = 0; i < m; i++) { for (int j = 0; j < n; j++) D[i][j] = A[i][j];} for (int i = 0; i < m; i++) { B[i] = n + i; D[i][n] = -1; D[i][n + 1] = b[i];} for (int j = 0; j < n; j++) { N[j] = j; D[m][j] = -c[j]; } N[n] = -1; D[m + 1][n] = 1; } void Pivot(int r, int s) { ld inv = 1.0 / D[r][s]; for (int i = 0; i < m + 2; i++) if (i != r) for (int j = 0; j < n + 2; j++) if (j != s) D[i][j] -= D[r][j] * D[i][s] * inv; for (int j = 0; j < n + 2; j++) if (j != s) D[r][j] *= inv; for (int i = 0; i < m + 2; i++) if (i != r) D[i][s] *= -inv; D[r][s] = inv; swap(B[r], N[s]); } bool Simplex(int phase) { int x = phase == 1 ? m + 1 : m; while (true) { int s = -1; for (int j = 0; j <= n; j++) { if (phase == 2 && N[j] == -1) continue; if (s==-1||D[x][j] -eps) return true; int r = -1; for (int i = 0; i < m; i++) { if (D[i][s] < eps) continue; if (r == -1 || D[i][n + 1] / D[i][s] < D[r][n + 1] / D[r][s] || ((D[i][n + 1]/D[i][s])==(D[r][n+1]/D[r][s])&&B[i]& x) { int r = 0; for (int i = 1; i < m; i++) if (D[i][n + 1] < D[r][n + 1]) r = i; if (D[r][n + 1] < -eps) { Pivot(r, n); if (!Simplex(1) || D[m + 1][n + 1] < -eps) return -inf; for (int i = 0; i < m; i++) if (B[i] == -1) { int s = -1; for (int j = 0; j <= n; j++) if (s==-1||D[i][j](n); for (int i = 0; i < m; i++) if (B[i] < n) x[B[i]] = D[i][n + 1]; return D[m][n + 1]; } }; vector > lpA; vector lpb; void addC(vector t, int s, int v){ vector r(400); for (int a:t){ if (s==1) r[a-1]=1; else r[a-1]=-1; } lpA.push_back(r); if (s==1) lpb.push_back(v); else lpb.push_back(-v); } vector g[444]; int p[444]; vector vs[444]; void dfs(int x, int d, int k){ vs[d].push_back(x); if (d==k){ vector c; while (d>0){ c.push_back(x); x=p[x]; d--; } addC(c, -1, 1); return; } for (int nx:g[x]){ if (nx!=p[x]){ p[nx]=x; dfs(nx, d+1, k); } } } int main(){ ios_base::sync_with_stdio(0); cin.tie(0); int n,k; cin>>n>>k; if (k*k>n) { cout<<"DA"<>a>>b; g[a].push_back(b); g[b].push_back(a); } dfs(1, 0, k); for (int i=1;i<=k;i++){ addC(vs[i], 1, 1); } vector lpc(400); for (int i=0;i<400;i++){ lpc[i]=1; } LPSolver lp(lpA, lpb, lpc); vector ans; ld val=lp.Solve(ans); if (val>0){ cout<<"DA"<