B"There is one gas station in each city of Berland. Gas stations have special pricing, and for each gas station there is a fixed range of prices for which they are ready to sell gasoline. A gas station in the city with the number i is ready to sell gasoline at any price from l_i to r_i inclusive. The King of Berland -- is an exemplary family man, and for m years, two sons were born to him every year. The king's children have been involved in public affairs since early childhood, and at the end of each year they check the honesty of gasoline prices. From birth, the king's children, who are born in the year i , are responsible for checking gasoline prices on the ways from the city of a_i to the city of b_i and from the city of c_i to the city of d_i , respectively. The check is as follows: both children simultaneously start their journey from the cities a_i and c_i , respectively. The first son of the king, born in the year i , moves along the path from the city a_i to the city b_i , and the second -- from the city c_i to the city d_i . Children check that the price of gasoline in the city of a_i coincides with the price of gasoline in the city of c_i . Next, they check that the price of gasoline in the second city on the way from a_i to b_i coincides with the price in the second city on the way from c_i to d_i . Then they repeat the same thing for a couple of third cities on their paths and so on. At the end, they check that the price of gasoline in the city of b_i coincides with the price of gasoline in the city of d_i . It is guaranteed that the length of the path from the city a_i to the city b_i coincides with the length of the path from the city c_i to the city d_i . Gas stations must strictly obey the laws, and therefore all checks of gasoline prices should not reveal violations. Help Berland "...