from collections import defaultdict
n=int(input())
edges=defaultdict(list)
for i in range(n-1):
    u,v=map(int,input().split())
    edges[u].append(v)
    edges[v].append(u)
res=[0]
d=[0]*(n+1)
def dfs(x,fa):
    for e in edges[x]:
        if e==fa:
            continue
        dfs(e,x)
        res[0]=max(res[0],d[x]+d[e]+1)
        d[x]=max(d[x],d[e]+1)
dfs(1,-1)
print(res[0])