#include <iostream>
#include <cstdio>
#include <queue>
#include <set>
using namespace std;
#define PII pair<int,int>

const int N = 100000;

set < PII > G[N];
set < PII >::iterator it;
int best[N];
int p[N];
int r[N];

int dijkstra( int a, int b, int n )
{
    priority_queue < PII, vector<PII>, greater<PII> > que;
    PII tmp, xd;

    for ( int i = 0; i < n; ++i ) best[i] = 100;

    que.push( make_pair(0, a) );
    best[a] = 0;
    while ( !que.empty() )
    {
        tmp = que.top(); que.pop();
        if ( tmp.second == b ) return tmp.first;
        if ( tmp.first > best[tmp.second] ) continue;

        for ( it=G[tmp.second].begin(); it != G[tmp.second].end(); ++it )
        {
            xd = make_pair( max( tmp.first, (*it).second ), (*it).first );
            if ( xd.first < best[xd.second] )
            {
                que.push(xd);
                best[xd.second] = xd.first;
            }
        }
    }
    return -1;
}

int Find( int a )
{
    if ( a == p[a] ) return a;
    else return ( p[a] = Find( p[a] ) );
}

void Union( int a, int b )
{
    a = Find( a ); b = Find( b );
    if ( a == b ) return;

    if ( r[a] < r[b] ) p[b] = a;
    else p[a] = b;
    if ( r[a] == r[b] ) r[a]++;
}

int main()
{
    int n, q, x, a, b, d;
    scanf( "%d%d", &n, &q );

    //for ( int i = 0; i < n; ++i ) p[i] = i;

    while ( q-- )
    {
        scanf( "%d", &x );
        if ( x == 0 )
        {
            scanf( "%d%d%d", &a, &b, &d );
            G[a].insert( make_pair( b, d ) );
            G[b].insert( make_pair( a, d ) );
            //Union( a, b );
        }
        else if ( x == 1 )
        {
            scanf( "%d%d", &a, &b );
            G[a].erase( G[a].lower_bound( make_pair( b, 0 ) ) );
            G[b].erase( G[b].lower_bound( make_pair( a, 0 ) ) );
        }
        else if ( x == 2 )
        {
            scanf( "%d%d", &a, &b );

            //for ( int i = 0; i < n; ++i ) cout << i << ": " << p[i] << " " << r[i] << endl;

            printf( "%d\n", dijkstra( a, b, n ) );
        }
    }
}