Question: The flag that was popularized in the Easter rising of 1916, has what three colors in it ?

Context articles: Dutch national flag problem
Michael Mallin
Easter Rising centenary parade
Tom Clarke (Irish republican)
First Day of the Easter Rising
Grötzsch's theorem
Tricolour (flag)
Flag of Ireland
Margaret Pearse
Pan-Slavic colors

The Dutch national flag problem (DNF) is a computer science programming problem proposed by Edsger Dijkstra.
 The flag of the Netherlands consists of three colors: red, white and blue.
 Given balls of these three colors arranged randomly in a line (the actual number of balls does not matter), the task is to arrange them such that all balls of the same color are together and their collective color groups are in the correct order.
Michael Thomas Christopher Mallin (Irish: "Micheál Ó Mealláin" ; 1 December 1874 – 8 May 1916) was an Irish rebel and socialist who took an active role in the 1916 Easter Rising.
 He was a silk weaver and co-founder with Francis Sheehy-Skeffington of the Irish Socialist Party, was second in command of the Irish Citizen Army under James Connolly in the Easter Rising of 1916 and commanded the garrison at St. Stephen's Green in Dublin, with Kit Poole as his second in command.
The Easter Rising centenary parade took place in Dublin city on Easter Sunday, 27 March 2016 to commemorate the Centenary of the Easter Rising.
 It involved all branches of the Defence Forces, including the Army, Air Corps, Naval Service and Reserve Defence Forces, as well as the Gardaí, Dublin Fire Brigade, the National Ambulance Service, the Irish Coast Guard, the Irish Prison Service and Customs, the Red Cross, the Coast Guard, the RNLI, the Civil Defence Ireland and St John Ambulance.
 The parade was one of the largest of its kind ever held in the state, involving over 3,700 military personnel, 78 vehicles and 17 aircraft.
 The events were broadcast on RTÉ television and it is estimated that around 1 million people viewed the parade across the streets of Dublin.
 The parade commenced at 10:30am from St. Stephen's Green and made its way along Dublin before stopping at O'Connell Bridge for the main Easter Sunday Commemoration at the GPO.
 Following the ceremony, the troops marched past the GPO in O'Connell Street before finishing at Bolton Street around 3pm.
Thomas James "Tom" Clarke (Irish: "Tomás Séamus Ó Cléirigh" ; 11 March 1858 – 3 May 1916) was an Irish republican revolutionary leader from Dungannon, County Tyrone.
 Clarke was arguably the person most responsible for the 1916 Easter Rising.
 A proponent of armed revolution for most of his life, he spent 15 years in English prisons prior to his role in the Easter Rising, and was executed after it was quashed.
The first day of the Easter Rising, Monday, April 24, 1916, saw some 1,200 volunteer soldiers of the Irish Volunteers take over positions in the centre of Dublin, launching the week-long revolution known as the Easter Rising.
In the mathematical field of graph theory, Grötzsch's theorem is the statement that every triangle-free planar graph can be colored with only three colors.
 According to the four-color theorem, every graph that can be drawn in the plane without edge crossings can have its vertices colored using at most four different colors, so that the two endpoints of every edge have different colors, but according to Grötzsch's theorem only three colors are needed for planar graphs that do not contain three mutually-adjacent vertices.
A tricolour or tricolor is a type of flag or banner design with a triband design which originated in the 16th century as a symbol of republicanism, liberty or indeed revolution.
 The flags of France, Italy, Romania, Mexico, and Ireland were all first adopted with the formation of an independent republic in the period of the French Revolution to the Revolutions of 1848, with the exception of the Irish tricolour, which dates from 1848 but was not popularised until the Easter Rising in 1916 and adopted in 1919.
The national flag of Ireland (Irish: "bratach na hÉireann" ) – frequently referred to as the Irish tricolour ("trídhathach na hÉireann") – is the national flag and ensign of the Republic of Ireland.
 The flag itself is a vertical tricolour of green (at the hoist), white and orange.
Margaret Pearse ("née" Brady; 12 February 1857 – 22 April 1932) was an Irish politician.
 She was born in Dublin, while her father's family were from County Meath.
 In 1877, she married James Pearse who was born in Bloomsbury, Middlesex on 8 December 1839.
 Margaret was the mother of Patrick Pearse, one of the leaders of the Easter Rising in 1916, who was executed soon after the rising.
 Another son Willie Pearse was also executed after the 1916 Easter Rising.
The Pan-Slavic colors — red, blue and white — were defined by the Prague Slavic Congress, 1848, based on the flag of Russia, which was introduced in the late 17th century.
 The tricolour flag of Russia was itself inspired by the flag of the Netherlands.
 Historically, many Slavic nations and states adopted flags and other national symbols that used some combination of those three colors, but rarely all three of them.
 List of Slavic countries that use or have used the colors include: Russia, Yugoslavia, Czechoslovakia, Czech Republic, Montenegro, Slovakia, Croatia, Serbia and Slovenia.
 Bosnia and Herzegovina, Belarus, Bulgaria, Macedonia, Poland and Ukraine have never adopted the colors.