N,M=map(int,input().split()) L=[{}for i in range(N+1)] for i in range(M): a,b,c=map(int,input().split()) if b in L[a]: L[a][b] = min(L[a][b],c) else: L[a][b] = c #print(L) import heapq for i in range(1,N+1): dist=[10**20 for i in range(N+1)] s=i Q=[(0,s)] heapq.heapify(Q) while len(Q)>0: d,p=heapq.heappop(Q) if dist[p]>d: dist[p]=d for k,v in L[p].items(): if dist[k]>(v+d): heapq.heappush(Q,(v+d,k)) ans=0 for i in dist[1:]: if i==10**20: continue else: ans+=i print(ans)