#include<bits/stdc++.h>
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) (int) (x).size()
#define pb push_back
#define fi first
#define se second

using namespace std;

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef long double LD;

const int MN = (int)1e5 + 5, P2 = (1 << 17), MTS = 2 * P2 + 5;
int ans[MTS];
VI T[MTS];

int ile[MN], par[MN], typ[MN], V[MN], S[MN];
map < PII, int > bylo;
PII E[MTS];

int curV, ost;

int Find(int x)
{
	while(x != par[x])
		x = par[x];
	return x;
}

void Union(int a, int b)
{
	++ost;
	a = Find(a);
	b = Find(b);
	if(a == b)
	{
		S[ost] = -1;
		return;
	}
	if(ile[a] > ile[b])
	{
		ile[a] += ile[b];
		par[b] = a;
		S[ost] = b;
	}
	else
	{
		ile[b] += ile[a];
		par[a] = b;
		S[ost] = a;
	}
}

void cof(int a)
{
	if(S[ost] == -1)
	{
		--ost;
		return;
	}
	a = Find(a);
	par[S[ost]] = S[ost];
	ile[a] -= ile[S[ost]];
	--ost;
}

void add(int a, int b, int v)
{
	a += P2, b += P2;
	while(a < b)
	{
		if(a & 1)
			T[a++].pb(v);
		if(!(b & 1))
			T[b--].pb(v);
		a >>= 1, b >>= 1;
	}
	if(a == b)
		T[a].pb(v);
}

void solve(int x)
{
	while(T[x].size() && V[T[x].back()] > curV)
		T[x].pop_back();
	int s = T[x].size();
	for(int i = 0; i < s; ++i)
		Union(E[T[x][i]].fi, E[T[x][i]].se);
	if(x >= P2)
	{
		int p = x - P2;
		if(Find(E[p].fi) == Find(E[p].se))
			ans[p] = curV;
	}
	else
	{
		solve(2 * x);
		solve(2 * x + 1);
	}
	for(int i = s - 1; i >= 0; --i)
		cof(E[T[x][i]].fi);
}

bool comp(int a, int b)
{
	return (V[a] < V[b]);
}

int main()
{
	int n, q;
	scanf("%d%d", &n, &q);
	for(int i = 1; i <= n; ++i)
	{
		par[i] = i;
		ile[i] = 1;
	}
	for(int i = 1; i <= q; ++i)
	{
		int t, x, y, v;
		scanf("%d", &t);
		typ[i] = t;
		if(t == 0)
		{
			scanf("%d%d%d", &x, &y, &v);
			++x, ++y;
			E[i] = {x, y};
			V[i] = v;
			bylo[E[i]] = i;
		}
		if(t == 1)
		{
			scanf("%d%d", &x, &y);
			++x, ++y;
			E[i] = {x, y};
			add(bylo[E[i]], i, bylo[E[i]]);
			bylo[E[i]] = 0;
		}
		if(t == 2)
		{
			scanf("%d%d", &x, &y);
			++x, ++y;
			E[i] = {x, y};
			ans[i] = -1;
		}
	}
	for(int i = 1; i <= q; ++i)
		if(typ[i] == 0 && bylo[E[i]] != 0)
		{
			add(bylo[E[i]], q + 1, bylo[E[i]]);
			bylo[E[i]] = 0;
		}
	for(int i = 1; i < MTS; ++i)
		sort(T[i].begin(), T[i].end(), comp);
	for(int i = 9; i >= 0; --i)
	{
		curV = i;
		solve(1);
	}
	for(int i = 1; i <= q; ++i)
		if(typ[i] == 2)
			printf("%d\n", ans[i]);
	return 0;
}