The photo taken on July 10, 2019 shows a limited edition metro card Troika with a giant panda image in Moscow, Russia. Moscow subway released a limited edition of 10,000 metro cards with Chinese giant panda images to mark the 155th anniversary of Moscow Zoo that accepted two giant pandas Ru Yi and Ding Ding in late April from China. (Photo: Xinhua)

The photo taken on July 10, 2019 shows a limited edition metro card Troika with a giant panda image in Moscow, Russia. Moscow subway released a limited edition of 10,000 metro cards with Chinese giant panda images to mark the 155th anniversary of Moscow Zoo that accepted two giant pandas Ru Yi and Ding Ding in late April from China. (Photo: Xinhua)

A passenger buys the limited edition of Moscow metro card Troika with a giant panda image in Moscow, Russia, on July 10, 2019. Moscow subway released a limited edition of 10,000 metro cards with Chinese giant panda images to mark the 155th anniversary of Moscow Zoo that accepted two giant pandas Ru Yi and Ding Ding in late April from China. (Photo: Xinhua)

The photo taken on July 10, 2019 shows a limited edition metro card Troika with a giant panda image in Moscow, Russia. Moscow subway released a limited edition of 10,000 metro cards with Chinese giant panda images to mark the 155th anniversary of Moscow Zoo that accepted two giant pandas Ru Yi and Ding Ding in late April from China. (Photo: Xinhua)