An Egyptian security guard screams at people as medics bring in a stretcher to carry the wounded after the attack which killed President Anwar Sadat, October 6, 1981, as he watched a military parade. (Photo by AP Photo)

Ray Yang, a celebrity trainer, takes a selfie before the start of a workout session during TV program "The Body Show" at a gym in Seoul, September 19, 2015. Looks no longer centre only on the face in beauty-obsessed South Korea, where more women are hitting the gym to improve muscle tone and physical health. As the ideal of beauty evolves in a country that is a trendsetter in cosmetics and the pursuit of plastic surgery, women's fitness has become a growth business, say purveyors of health products, from diet supplements to dumb-bells. (Photo by Kim Hong-Ji/Reuters)

People attend a Halloween event at Ocean Park on October 30, 2015 in Hong Kong. Halloween – a named taken from 'All Hallows' Even' falls on the day before All Saints' Day on November 1 – a holiday when Christians remember their deceased loved ones. (Photo by Anthony Kwan/Getty Images)

A photographer takes a snapshot of the reflection of balloons as they take off from Balloon fiesta park in Corrales, N.M., near a north diversion channel reservoir Wednesday, October 7, 2015. (Photo by Roberto E. Rosales/Albuquerque Journal via AP Photo)

These beautiful shots may look like works of modern art – but they are actually close-ups of chemical reactions. The works were snapped with the help of a group of scientists from the University of Science and Technology of China (USTC) in Anhui, China. Here: Zinc reacting with lead nitrate in a soft gel to form lead crystals. (Photo by Yan Liang/Caters News)

A Brussels Airlines aircraft prepares for landing in Cointrin airport during sunrise over the Mont Blanc in Geneva December 1, 2011. (Photo by Denis Balibouse/Reuters)

National Geographic invites photographers from around the world to enter the 2013 National Geographic Photography Contest. The grand-prize winner will receive $10,000 (USD) and a trip to National Geographic headquarters in Washington, D.C., to participate in the annual National Geographic Photography Seminar in January 2014. Photo: “We just want to move to search to the Leopard at that morning but we found a group of giraffes come toward a small lake and start drinking it was a nice moment when the Giraffe finish from drinking and leave a letters “S” with motion in the air”. (Photo and caption by Majed Ali/National Geographic Photography Contest)

Bollywood actress Chitrashi Rawat lies in a plastic drum as she is briefed by a crew member during the shoot for the film “Black Home” at a beach on the outskirts of Mumbai April 26, 2013. (Photo by Danish Siddiqui/Reuters)