func_code_string: #include <bits/stdc++.h>   using namespace std;   int A[200005], B[200005], N;   int O[200005][5];   void ucitaj() {     scanf( %d , &N);     if (N == 5) {       printf( 1 5 3 4 2 n );       exit(0);     }     int i, j;     for (i = 1; i <= 2 * N; i++) {       scanf( %d%d , A + i, B + i);       if (O[A[i]][1] == 0)         O[A[i]][1] = B[i];       else if (O[A[i]][2] == 0)         O[A[i]][2] = B[i];       else if (O[A[i]][3] == 0)         O[A[i]][3] = B[i];       else         O[A[i]][4] = B[i];       if (O[B[i]][1] == 0)         O[B[i]][1] = A[i];       else if (O[B[i]][2] == 0)         O[B[i]][2] = A[i];       else if (O[B[i]][3] == 0)         O[B[i]][3] = A[i];       else         O[B[i]][4] = A[i];     }   }   bool Sus6[10][10];   bool susedi(int a, int b) {     if (Sus6[a][b]) return false;     return O[a][1] == b || O[a][2] == b || O[a][3] == b || O[a][4] == b;   }   bool susedi6(int a, int b) {     return O[a][1] == b || O[a][2] == b || O[a][3] == b || O[a][4] == b;   }   void sus6() {     int i, j, k;     for (i = 1; i <= 6; i++) {       for (j = i + 1; j <= 6; j++) {         for (k = i + 1; k <= 6; k++) {           if (susedi6(i, j) && susedi6(j, k) && susedi6(i, k)) {             Sus6[i][j] = true;             Sus6[i][k] = true;             Sus6[k][j] = true;             Sus6[k][i] = true;             Sus6[j][k] = true;             Sus6[j][i] = true;           }         }       }     }   }   void probaj(int *A) {     int i, j;     if (!susedi6(A[1], A[2])) return;     if (!susedi6(A[2], A[3])) return;     if (!susedi6(A[3], A[4])) return;     if (!susedi6(A[4], A[5])) return;     if (!susedi6(A[5], A[6])) return;     if (!susedi6(A[6], A[1])) return;     if (!susedi6(A[1], A[3])) return;     if (!susedi6(A[2], A[4])) return;     if (!susedi6(A[3], A[5])) return;     if (!susedi6(A[4], A[6])) return;     if (!susedi6(A[5], A[1])) return;     if (!susedi6(A[6], A[2])) return;     if (susedi6(A[1], A[4])) return;     if (susedi6(A[2], A[5])) return;     if (susedi6(A[3], A[6])) return;     for (i = 1; i <= 6; i++) printf( %d n , A[i]);     exit(0);   }   int S1[200005], S2[200005];   void ubaci() {     int i, j, k, l, u, v;     if (N == 6) {       sus6();       for (i = 1; i <= N; i++) A[i] = i;       for (i = 1; i <= 720; i++) {         probaj(A);         next_permutation(A + 1, A + 7);       }       printf( -1 n );       exit(0);     }     for (i = 1; i <= 2 * N; i++) {       u = A[i];       v = B[i];       k = 0;       if (O[u][1] == O[v][1]) k++;       if (O[u][2] == O[v][1]) k++;       if (O[u][3] == O[v][1]) k++;       if (O[u][4] == O[v][1]) k++;       if (O[u][1] == O[v][2]) k++;       if (O[u][2] == O[v][2]) k++;       if (O[u][3] == O[v][2]) k++;       if (O[u][4] == O[v][2]) k++;       if (O[u][1] == O[v][3]) k++;       if (O[u][2] == O[v][3]) k++;       if (O[u][3] == O[v][3]) k++;       if (O[u][4] == O[v][3]) k++;       if (O[u][1] == O[v][4]) k++;       if (O[u][2] == O[v][4]) k++;       if (O[u][3] == O[v][4]) k++;       if (O[u][4] == O[v][4]) k++;       if (k == 2) {         if (S1[u] == 0)           S1[u] = v;         else           S2[u] = v;         if (S1[v] == 0)           S1[v] = u;         else           S2[v] = u;       }     }   }   bool V[200005];   int Red[200005], RRR;   void obidji() {     int i, j, k;     k = 1;     j = 1;     V[1] = true;     Red[++RRR] = 1;     while (k < N) {       if (!V[S1[j]]) {         j = S1[j];         V[j] = true;       } else if (!V[S2[j]]) {         j = S2[j];         V[j] = true;       } else {         printf( -1 n );         exit(0);       }       Red[++RRR] = j;       k++;     }     for (i = 1; i <= N; i++) printf( %d%c , Red[i], i == N ?   n  :    );   }   int main() {     ucitaj();     ubaci();     obidji();     return 0;   }   