how to access Nested routes

export const appRouter = t.router({
    show: t.procedure.query(async () => {
        const cities: Cities[] = await db.select().from(city);
        return cities;
    }),
   
    auth: authRouter,
})

export const appRouter = t.router({
    show: t.procedure.query(async () => {
        const cities: Cities[] = await db.select().from(city);
        return cities;
    }),
   
    auth: authRouter,
})

export const authRouter = t.router({
    log: t.procedure.query(async () => {
        const cities: Cities[] = await db.select().from(city);
        return cities;
    })

})

export const authRouter = t.router({
    log: t.procedure.query(async () => {
        const cities: Cities[] = await db.select().from(city);
        return cities;
    })

})