Well, according to the UN, in the two years since Russia's invasion, 6 million people, mainly women and children, have fled the country. Millions more have been forced to live under Russian occupation in a number of areas. Little is known about their lives. But as our reporter, Olga Malchevska, has been finding out, she talked to two teenagers, one from Mariupol, the other Kherson, who were rescued from Russian occupation. They've just been here in London sharing what they witnessed with politicians.

They look like ordinary teenagers visiting London, but they are survivors of war.

Our village was shelled.

A friend of my aunt came and took us to Mariupol. We thought we would be safer there because they wouldn't shell the city itself.

Two, three days later, our village was occupied.

Then, Mariupol City was besieged. It was a hell. We wanted to go back, but it was impossible.

Veronika is from Herson in the south of Ukraine.

Our city was occupied for seven months. After it, it became a frontline during the occupation, there were lots of shelling in the smaller towns or villages.

We were sitting in the basement for a month.

When we left the basement, two shells landed near me.

It was very scary. The sound of missiles gives me goosebumps. It's like a loud whistle, and then a blast. It gets closer and louder and louder. It's extremely frightening.

Russia denies that it targets civilians.

Russian soldiers took my phone.

I had deleted all my social media as I knew that they wouldn't like my chats. They asked if I knew anything about Ukrainian servicemen, and I said I didn't, but I felt scared. And they said, Don't worry. If we wanted to kill you, we would already done so.

What was the most dramatic memory of yours?

While we moved from the occupied city, we saw lots of cars that were burned.

I saw people coming inside their tent and later coming out of it naked.

Some people were also beaten. People were tortured in various ways there. I heard screaming, Don't hit me, please.

' Veronika's family had to cross the Dnipro River on a makeshift ferry. As the breach had been bombed.

Too emotional to speak in English, Veronika tells me how her parents stressed out when they got stuck in the middle of the river for two hours.

The makeshift ferry was shelled just half an hour after they got to the other side.

I had so many problems, but I keep smiling because I want to. It's not like I'm faking a smile while feeling sad in reality, but no, I want to smile because I'm alive.

Olga Malchewska, BBC News.