Question: Who is Leszek, Duke Of Masovia's paternal grandfather?

Knowledge 1: Leszek, Duke of Masovia
Leszek of Masovia (also "Lestek")(b. ca.1162 - d. 1186) was a Polish prince from the Piast dynasty, the Duke of Masovia from 1173 until his death.He was the only son of Bolesław IV the Curly, Duke of Masovia and High Prince of Polan, who survived father.After his father death he inherited Masovia.At the beginning, Leszek ruled under the guardianship of his uncle Casimir IIthe Just.He was a man of poor health.For a short time he supported his other uncle, Mieszko III the Old, but later decided to reconciled with Kazimierz II, who after Leszek's death inherited his duchy. [SEP] Knowledge 2: Bolesław IV the Curly
Bolesław IV the Curly (also known as Boleslaus IV the Curly) (ca. 1125 – 5 January 1173) of the Piast dynasty was Duke of Masovia from 1138 and High Duke of Poland from 1146 until his death.He was the third son of Duke Bolesław III Wrymouth of Poland by his second wife Salomea, daughter of the Swabian count Henry of Berg.The death of his older brothers, Leszek and Casimir, before 1131 and in October 1131, respectively, left him as the eldest son of their parents.
Knowledge 1: Leszek, Duke of Masovia
Leszek of Masovia (also "Lestek")(b. ca.1162 - d. 1186) was a Polish prince from the Piast dynasty, the Duke of Masovia from 1173 until his death.He was the only son of Bolesław IV the Curly, Duke of Masovia and High Prince of Polan, who survived father.After his father death he inherited Masovia.At the beginning, Leszek ruled under the guardianship of his uncle Casimir IIthe Just.He was a man of poor health.For a short time he supported his other uncle, Mieszko III the Old, but later decided to reconciled with Kazimierz II, who after Leszek's death inherited his duchy. [SEP] Knowledge 2: Konrad I of Masovia
Konrad I of Masovia( ca. 1187/88 – 31 August 1247), from the Polish Piast dynasty, was the sixth Duke of Masovia and Kujawy from 1194 until his death as well as High Duke of Poland from 1229 to 1232 and again from 1241 to 1243.
Knowledge 1: Leszek, Duke of Masovia
Leszek of Masovia (also "Lestek")(b. ca.1162 - d. 1186) was a Polish prince from the Piast dynasty, the Duke of Masovia from 1173 until his death.He was the only son of Bolesław IV the Curly, Duke of Masovia and High Prince of Polan, who survived father.After his father death he inherited Masovia.At the beginning, Leszek ruled under the guardianship of his uncle Casimir IIthe Just.He was a man of poor health.For a short time he supported his other uncle, Mieszko III the Old, but later decided to reconciled with Kazimierz II, who after Leszek's death inherited his duchy. [SEP] Knowledge 2: Sophia of Masovia
Sophia of Masovia( 1497/1498- before 11 March 1543) was a Princess of Masovia, daughter of Konrad III Rudy, Duke of Masovia and his wife Anna Radziwiłł.She was a member of the House of Piast.On 17 September 1520 in Warsaw, Sophia was married by proxy to Stephen VII Báthory.On 17 January 1521, Sophia and her entourage went to Hungary, where in February there was a formal marriage.The couple had three children:Anna, Stephen and Klara; however, other sources claim that Klara was the couple's only child.Klara was engaged to Carl, Duke of Münsterberg, but died in 1535, before the marriage took place.After the death of Stephen in 1530, Sophia was married to Croatian magnate Louis Pekry.Sophia's second marriage was childless.She then died sometime before 11 March 1543.Sophia had three siblings: Stanislaus I of Masovia, Janusz III of Masovia and Anna of Masovia, both her brothers died childless and so Anna and Sophia were the last Masovian Piasts.Soon after Janusz's death, the Duchy of Masovia was annexed into the kingdom of Poland, despite resistance from some of the Masovian nobility.They tried to retain their independence and argued that the Duchy should be inherited by the female relatives( such as Anna or Sophia).The Polish king refused to recognize their demands.Anna was made titular Duchess of Masovia.

Answer: Bolesław III Wrymouth