People gather on the square to see the lights of the Christmas tree in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

People gather on the square to see the lights of the Christmas tree in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

Christmas decorations are seen at the Christmas market in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

People buy Christmas decorations at the Christmas market in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

People gather on the square to see the lights of the Christmas tree in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

People gather on the square to see the lights of the Christmas tree in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

The Christmas tree is lit up in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

People gather on the square to see the lights of the Christmas tree in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

People gather on the square to see the lights of the Christmas tree in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.

People gather on the square to see the lights of the Christmas tree in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened. (Photos: Xinhua)

People gather on the square to see the lights of the Christmas tree in Prague, the Czech Republic, Nov. 30, 2019. With the lightening ceremony of the 22-meter-high Christmas tree Saturday evening on the Old Town Square in downtown Prague, the traditional Christmas market officially opened.