#include <bits/stdc++.h>

using namespace std;

vector< int > edge[800005];
bool vis[800005];
int lvl[800005];

void bfs( int src )
{
    queue < int > q;
    memset( vis, 0, sizeof vis );
    memset( lvl, 0, sizeof lvl );

    q.push( src );
    vis[ src ] = true;
    while( !q.empty() ){
        int u = q.front();
        q.pop();

        for( int i = 0; i<edge[u].size(); i++){
            if( !vis[edge[u][i]] ){
                int v =edge[u][i];
                vis[v] = true;
                lvl = lvl[u]+1;
                q.push( v );
            }
        }
    }
}

int main() {
    int T, n, x, y, m, s, e;
    cin >> T;
    while( T-- && cin >> n >> m ) {
        for(int i=0; i<=m; i++) edge[i].clear();
        int ara[m+5];
        for( int i=1; i<=n; i++){
            cin >> ara[i];
        }
        while( n-- ) {
            cin >> x >> y;
            edge[ x ].push_back( y );
            edge[ y ].push_back( x );
        }
        cin >> s >> e;
        bfs( s );
        cout << lvl[e] << endl;

    }
    return 0;
}