import sys import heapq def main(): input = sys.stdin.read().split() ptr = 0 N = int(input[ptr]) ptr += 1 M = int(input[ptr]) ptr += 1 adj = [[] for _ in range(N+1)] # 1-based for _ in range(M): k_i = int(input[ptr]) ptr +=1 c_i = int(input[ptr]) ptr +=1 s_i = list(map(int, input[ptr:ptr+k_i])) ptr +=k_i s1 = s_i[0] for u in s_i: if u == s1: continue w = (u + s1 + 1) // 2 + c_i adj[u].append( (s1, w) ) adj[s1].append( (u, w) ) # Dijkstra's INF = float('inf') dist = [INF] * (N+1) dist[1] = 0 heap = [] heapq.heappush(heap, (0, 1)) while heap: d, u = heapq.heappop(heap) if d > dist[u]: continue for v, w in adj[u]: if dist[v] > d + w: dist[v] = d + w heapq.heappush(heap, (dist[v], v)) if dist[N] == INF: print(-1) else: print(dist[N]) if __name__ == '__main__': main()