class UNSET():
    def __init__(self, n):
        self.n = n 
        self.pre = list(range(n))

    def find(self, i):
        if i != self.pre[i]: self.pre[i] = self.find(self.pre[i])
        return self.pre[i]

    def un(self, i, j):
        fi, fj = self.find(i), self.find(j)
        if fi != fj:
            self.pre[fi] = fj     

def kruskal(n, e):
    from heapq import heappop, heappush
    us = UNSET(n)
    q = []
    for u in range(n):
        for d, v in e[u]: q.append([d, u, v]) 
    q.sort()
    res = 0 
    for d, u, v in q:
        fu, fv = us.find(u), us.find(v)
        if fu != fv: res += d; us.un(u, v)
    return res