Task: Question Answering
Input (English): Passage: Brian's body was brought to Swords, north of Dublin. There it was met by the coarb of Patrick, the traditional head of the church in Ireland, who brought the body back with him to Armagh, where it was interred after twelve days of mourning. Along with Brian were the body of Murchad and the heads of Conaing, Brian's nephew, and Mothla, King of the Déisi Muman. Máel Sechnaill was restored as High King of Ireland, and remained secure in his position until his death in 1022. Though the Annals imply that life was not much changed after the death of Brian Boru, it created a succession crisis, as Brian's son and heir Murchad had died as well. Brian had two remaining sons who could challenge for the kingship: Donnchad mac Briain, his son with Gormflaith and Tadc mac Briain, his son with Echrad. According to the annals, Donnchad rallied the forces of the Dál gCais at Clontarf and lead them home to Cenn Corad. Within weeks the Dál gCais, under the new leadership of Donnchad, were battling their old masters the Eóganacht Raithlind. Tadc initially joined his brother against the Eóganacht, but would eventually be killed in 1023 at the order of Donnchad. Sigtrygg remained King of Dublin until 1036, and was apparently secure enough to go on pilgrimage to Rome in 1028. However, after Clontarf, Dublin had been reduced to a lesser power. In 1052, Diarmait mac Máel na mBó, King of Leinster, captured Dublin and Fine Gall, for the first time asserting Irish overlordship over the Norse of Ireland. 
Question: How many sons did Brian have? 
Answer type: Number 
Output (English): 3.