import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop, core.stdc.string;

immutable long MOD = 10^^9 + 7;

void main() {
    auto N = readln.chomp.to!int;
    auto G = new int[][](N);
    foreach (_; 0..N-1) {
        auto s = readln.split.map!(to!int);
        G[s[0]-1] ~= s[1]-1;
        G[s[1]-1] ~= s[0]-1;
    }

    Tuple!(int, int) dfs(int n, int p, int d) {
        Tuple!(int, int) ret = tuple(d, n);
        foreach (m; G[n]) {
            if (m == p) continue;
            ret = max(ret, dfs(m, n, d+1));
        }
        return ret;
    }

    auto x = dfs(0, -1, 0);
    auto y = dfs(x[1], -1, 0);

    writeln(N - y[0] - 1);
}