thinkorswim® by td ameritrade new densify from crest pro-health. like bones, your teeth lose density over time, but crest has you covered. crest densify actively rebuilds tooth density to extend the life of teeth. crest, the number one toothpaste brand in america. >> diaz: russia's >> diaz: russia's invasion has put a spotlight on ukraine's defiant president, volodymyr zelensky, now a symbol of his country's resistance.nce. it's also renewed interes it's also renewed interest in his unconventional path to politics. cbs' holly williams has his backstory. >> reporter: ukraine's president, volodymyr zelensky, is being hailed as a new winston churchill. stoically refusing to leave his country, even as the bombs rain down, sending words of inspiration to his people.