func_code_string: #include <bits/stdc++.h>   using namespace std;   inline long long read() {     long long sum = 0, ff = 1;     char ch = getchar();     while (ch <  0  || ch >  9 ) {       if (ch ==  - ) {         ff = -1;       }       ch = getchar();     }     while (ch >=  0  && ch <=  9 ) {       sum = sum * 10 + ch - 48;       ch = getchar();     }     return sum * ff;   }   void write(long long x) {     if (x < 0) putchar( - ), x = -x;     if (x > 9) write(x / 10);     putchar(x % 10 +  0 );   }   const int N = 1000007;   int n, m;   struct edge {     int from, to, dis, next;   } e[N], a[N];   int he[N], cnt;   void add(int u, int v, int w) {     e[++cnt].from = u;     e[cnt].to = v;     e[cnt].dis = w;     e[cnt].next = he[u];     he[u] = cnt;   }   bool cmp(edge x, edge y) {     if (x.from == y.from) return x.to < y.to;     return x.from < y.from;   }   int col[N];   queue<int> q;   struct node {     int pos, dis;   };   queue<node> que;   bool vis[N];   int bfs() {     que.push((node){n, 0});     vis[n] = true;     while (!que.empty()) {       node now = que.front();       que.pop();       if (now.pos == 1) return now.dis;       for (int i = he[now.pos]; i; i = e[i].next) {         int v = e[i].to;         if (vis[v]) continue;         if (col[v] == -1 || col[v] == 1 - e[i].dis)           col[v] = 1 - e[i].dis;         else {           vis[v] = true;           que.push((node){v, now.dis + 1});         }       }     }     return -1;   }   map<pair<int, int>, bool> mp;   int main() {     n = read(), m = read();     for (int i = 1; i <= m; i++) {       a[i].from = read(), a[i].to = read(), a[i].dis = read();       add(a[i].to, a[i].from, a[i].dis);     }     memset(col, -1, sizeof(col));     write(bfs()), puts(  );     for (int i = 1; i <= n; i++)       if (col[i] == -1)         printf( 0 );       else         write(col[i]);     return 0;   }   