#ifndef LOCAL
#define FAST_IO
#endif

// ============
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#define OVERRIDE(a, b, c, d, ...) d
#define REP2(i, n) for (i32 i = 0; i < (i32) (n); ++i)
#define REP3(i, m, n) for (i32 i = (i32) (m); i < (i32) (n); ++i)
#define REP(...) OVERRIDE(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define PER(i, n) for (i32 i = (i32) (n) - 1; i >= 0; --i)
#define ALL(x) begin(x), end(x)

using namespace std;

using u32 = unsigned int;
using u64 = unsigned long long;
using u128 = __uint128_t;
using i32 = signed int;
using i64 = signed long long;
using i128 = __int128_t;
using f64 = double;
using f80 = long double;

template <typename T>
using Vec = vector<T>;

template <typename T>
bool chmin(T &x, const T &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T>
bool chmax(T &x, const T &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}

istream &operator>>(istream &is, i128 &x) {
    i64 v;
    is >> v;
    x = v;
    return is;
}
ostream &operator<<(ostream &os, i128 x) {
    os << (i64) x;
    return os;
}
istream &operator>>(istream &is, u128 &x) {
    u64 v;
    is >> v;
    x = v;
    return is;
}
ostream &operator<<(ostream &os, u128 x) {
    os << (u64) x;
    return os;
}

[[maybe_unused]] constexpr i32 INF = 1000000100;
[[maybe_unused]] constexpr i64 INF64 = 3000000000000000100;
struct SetUpIO {
    SetUpIO() {
#ifdef FAST_IO
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
#endif
        cout << fixed << setprecision(15);
    }
} set_up_io;
// ============

#ifdef DEBUGF
#else
#define DBG(x) (void) 0
#endif

// ============

#include <cassert>
#include <utility>
#include <vector>

class UnionFind {
    std::vector<int> par;

    int _root(int v) {
        if (par[v] < 0) {
            return v;
        } else {
            return par[v] = _root(par[v]);
        }
    }

public:
    UnionFind(int n) : par(n, -1) {}

    int root(int v) {
        assert(v >= 0 && v < (int) par.size());
        return _root(v);
    }

    int size(int v) {
        assert(v >= 0 && v < (int) par.size());
        return -par[_root(v)];
    }

    bool unite(int u, int v) {
        assert(u >= 0 && u < (int) par.size() && v >= 0 && v < (int) par.size());
        u = _root(u);
        v = _root(v);
        if (u == v) {
            return false;
        }
        if (par[u] < par[v]) {
            std::swap(u, v);
        }
        par[v] += par[u];
        par[u] = v;
        return true;
    }

    bool same(int u, int v) {
        assert(u >= 0 && u < (int) par.size() && v >= 0 && v < (int) par.size());
        return _root(u) == _root(v);
    }
};

// ============

int main() {
    i32 n, m;
    cin >> n >> m;
    Vec<i32> u(m), v(m);
    REP(i, m) {
        cin >> u[i] >> v[i];
        --u[i];
        --v[i];
    }
    
    UnionFind uf(n);
    Vec<i32> mx(n, 0);
    PER(i, m) {
        i32 ru = uf.root(u[i]);
        i32 rv = uf.root(v[i]);
        if (ru == rv) {
            ++mx[ru];
        } else {
            i32 m = max(mx[ru], mx[rv]) + 1;
            uf.unite(ru, rv);
            mx[uf.root(ru)] = m;
        }
    }
    cout << *max_element(ALL(mx)) << '\n';
}