func_code_string: #include <bits/stdc++.h>   using namespace std;   const int mxn = 100006;   const int mxm = 100006 * 2;   int n, m;   int fe[mxn] = {};   int ne[mxm];   int ev[mxm];   bool v[mxm];   int el = 1;   void add1(int L, int R) {     ++el;     ne[el] = fe[L];     fe[L] = el;     ev[el] = R;   }   bool vis[mxn];   int dfs(int x) {     if (vis[x]) return 0;     vis[x] = true;     int last = 0;     for (int i = fe[x]; i; i = ne[i])       if (!v[i]) {         v[i] = v[i ^ 1] = true;         int t = dfs(ev[i]);         if (t) {           printf( %d %d %d n , x, ev[i], t);         } else {           if (last) {             printf( %d %d %d n , last, x, ev[i]);             last = 0;           } else {             last = ev[i];           }         }       }     return last;   }   void EXEC() {     cin >> n >> m;     if (m % 2 == 1) {       cout <<  No solution  << endl;       return;     }     for (int i = 0; i < m; ++i) {       int L, R;       scanf( %d%d , &L, &R);       add1(L, R);       add1(R, L);     }     dfs(1);   }   int main() {     EXEC();     return 0;   }   