Context: [[Hrothgar]], king of Danelands, and a group of mounted and helmeted warriors chase a large and burly man, whom they consider a monstrous [[troll]], and his young son across a large open field until father and son find themselves on the edge of deep cliff overlooking a beach and a large sea. The father directs his young son, [[Grendel]], to climb down and hide from the attackers' view. The Danes shoot the father dead with their arrows and his dead body plunges down onto the beach far below. The Danish king walks towards the cliff edge and sees the young Grendel hanging but chooses to spare him.Later, Grendel is on the beach below and finds his father's body. After failing to move the large and heavy corpse, the boy takes a sword and cuts the head off to take it home.Many years later, the severed (and mummified) head is inside a cave where the boy Grendel has grown up to be as large and burly as his father. Grendel bloodies his own forehead with stones to express his vengeful anger towards the Danes and the beginning of his own murderous campaign of revenge.When Hrothgar finds twenty of his warriors killed inside his great hall, the Danish king falls into a depression. [[Beowulf (hero)|Beowulf]], with the permission of [[Hygelac]], king of [[Gotaland|Geatland]], sails to Daneland with thirteen Geats on a mission to slay Grendel for Hrothgar.The arrival of Beowulf and his warriors is welcomed by Hrothgar, but the king's village has fallen into a deep despair and many of the pagan villagers convert to Christianity at the urging of an [[Irish monk]]. While Grendel does go into Hrothgar's village during the night, he flees rather than fight.Beowulf learns more about Grendel from Selma the witch and seer, who tells Beowulf that Grendel will not fight him because Beowulf has committed no wrong against him. A villager, recently baptized and thus now unafraid of death, leads Beowulf and his men to the cliff above Grendel's cave, but without a rope they are afraid to die descending to the cave itself, and turn back without even seeing the cave. When that villager is found broken and dead, Beowulf and his men return with a rope and gain entry to Grendel's secret cave. Grendel being absent, one of Beowulf's vengeful men mutilates the mummified head and shrine of Grendel's slain father.That night, Grendel attacks Beowulf and his men while they sleep in Hrothgar's great hall, killing the Geat who desecrated his father's head and then, revenge satisfied, leaps out from the second story, but is caught in a trap by Beowulf, leaving Grendel hanging by his right arm. Grendel, refusing capture, escapes by hacking off his own arm. Grendel, bleeding severely, manages to reach the same beach where he had once found his father's slain corpse and wades into the water, where he dies, his body claimed by a mysterious webbed hand. Hrothgar admits to Beowulf that he had killed Grendel's father for stealing a fish but had spared the child-troll Grendel out of pity.There is great celebration in the hall of Hrothgar, and the king's mood has been livened up by the defeat of Grendel, whose severed arm is kept by the Danes as a trophy.In revealing more about Grendel's nature, Selma recounts how Grendel had once visited her hut and clumsily raped her and has protected her since that day, troubling Beowulf all the more. Yet that does not stop him from moving forward to kiss Selma, who deftly slaps him for tying her up earlier in the film, which he did in an attempt to get her to lead him to Grendel. Nevertheless, she then pulls his head forward and kisses him, quickly initiating and taking the lead in their lovemaking as she straddles him down on her bed.The Danes are later attacked by [[Grendel's mother]], the Sea Hag. Beowulf finds her lair, where she placed Grendel's dead body along with a pile of treasure, and slays Grendel's mother with 
 Question: How many of his warriors does Hrothgar find killed?
Output: twenty