dfs

int main()
{
    #ifndef ONLINE_JUDGE
    //freopen("cin.txt","r",stdin);
    //freopen("cout.txt","w",stdout);
    #endif // ONLINE_JUDGE
    //speed
    int t=Int;
    while(t--){
        int n=Int,e=Int;
        vector<int> adj[n+1];
        for(int a=1;a<=e;a++){
            int x=Int,y=Int;
            if(x>y)swap(x,y);
            adj[x].pb(y);
        }
        stack<int> dfs;
        dfs.push(1);
        int distance[n+1]={0};
        int color[n+1]={0};
        while(!dfs.empty()){
            int top=dfs.top();
            bool found=false;
            for(int a=0;a<adj[top].size();a++){
                int u=top,v=adj[top][a];
                if(color[v]==0){
                    dfs.push(v);
                    distance[v]=distance[u]+1;
                    color[v]=1;
                    found=true;
                }
            }
            if(!found){
                dfs.pop();
            }
        }
        cout<<distance[n]<<endl;
    }
    r0;
}