Can a Sunni pray in a Shia congregation/mosque being lead by a Shia Imam?

Let say that it's prayer time... and suddenly a Sunni see everybody went to a mosque... he joined the crowd and pray in the congregation... when he went off the mosque .. suddenly someone tell him that it's a Shia mosque.

Does that prayer valid?

I believe they only pray 3 times rather than the 5 required otherwise the prayer is similar.. but I don't know..

3 prayers?

I never seen how Shiites pray...

But can we go to their mosque and do individual prayer?

akhi.. I really don't know ( I am sorry).. I had a friend in under-grad who was/is lebanese, for the longest time I didn't know she was a shiite...I notice only by the prayers missed one day.. the other thing that was stricking is the males always take their belt off when praying.. when I asked her about this, she stated they are not allowed to wear anything made from animals.. of course i was hot and fervent then to change people... I spoke to her about what she was doing, she said I was in no position to tell her anything when there are so many Muslims who don't pray all together... sadest part is she was from a sunni family.. and I know exactly the member that got her to be a shiite... either way it is her business.. just wish I knew then what I know now..

Assalaamu Alaikum Wa Rahmatulaahi Wa Barakatuh

Upon that thread closed.