gre = [[(0, 0, True), (0, 1, False), (0, 2, False), (0, 3, False)],
[(1, 0, True), (1, 1, True), (1, 2, False), (1, 3, False)],
[(2, 0, True), (2, 1, True), (2, 2, True), (2, 3, False)],
[(3, 0, True), (3, 1, True), (3, 2, True), (3, 3, True)]];
i=0
j=0
while i < len (gre):
j = 0
while j < len (gre [i]):
if gre [i][j][2]:
print (gre [i][j])
j = j + 1
i = i + 1