Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)

Ballet show "Swan Lake" is performed by Russian theater "The crown of Russian ballet" at Jahrhunderthalle in Frankfurt, Germany, on Feb. 25, 2019. (Xinhua/Lu Yang)