Medic James E. Callahan of Pittsfield, Mass., gives mouth-to-mouth resuscitation to a dying soldier in war zone D, about 50 miles northeast of Saigon, June 17, 1967. Thirty-one men of the 1st Infantry Division were reported killed in the guerrilla ambush, with more than 100 wounded. (Photo by Henri Huet/AP Photo)

Ice swimmer Klaudia prepares to swim in a filled up water kettle in an ice cave inside the Nature Ice Palace, with a hight of 3,250 meters (10,663 feet) above sea level, at Hintertux Glacier near Hintertux, some 480 kilometers (298 miles) western of Vienna, Austria, 28 July 2018. (Photo by Christian Bruna/EPA/EFE)

In this November 26, 2018 photo, men run during 100 meters athletics competition of the second edition of the Panamanian indigenous games in Piriati, Panama. These games were held in the Embera town of Piriati, some 55 miles (90 kilometers) east of Panama City. (Photo by Arnulfo Franco/AP Photo)

Bangladeshi relatives wail near bodies of victims after a river ferry carrying about 100 passengers capsized Sunday after being hit by a cargo vessel,in Manikganj district, about 40 kilometers (25 miles) northwest of Dhaka, Bangladesh, Sunday, February 22, 2015. (Photo by A. M. Ahad/AP Photo)

Geese fight during the annual Geese Fight Day in the northern Serbian village of Mokrin, some 160km (100 miles) from Belgrade February 22, 2015. Every year in the last week of February, goose fights are held in the northern Serbian village of Mokrin. Left alone, male geese, or ganders, are unlikely to fight each other, hence why females are brought along for whose affections the ganders then fight until one or the other gives up. (Photo by Marko Djurica/Reuters)

An unmanned Falcon 9 SpaceX rocket lifts off from launch complex 40 at the Cape Canaveral Air Force Station, Wednesday, February 11, 2015, in Cape Canaveral, Fla. On board is the Deep Space Climate Observatory, which will head toward a solar-storm lookout point a million miles away. (Photo by John Raoux/AP Photo)

Children of local herders gather at a reindeer camping ground, some 200 km (124 miles) northeast of Naryan-Mar, the administrative centre of Nenets Autonomous Area, far northern Russia, August 2, 2015. People, including local herders and members of their families, gathered at the site to mark Reindeer Day, a professional holiday of reindeer breeding workers, which is celebrated annually on August 2 in the region. (Photo by Sergei Karpukhin/Reuters)

A musher handler with Alan Eischens team embraces one of Eischen's dogs just before the ceremonial start of the Iditarod Trail Sled Dog Race that begins a near 1,000-mile (1,600-km) journey through Alaska’s frigid wilderness in downtown Anchorage, Alaska March 5, 2016. (Photo by Nathaniel Wilder/Reuters)