# Write a function that accepts an array of integers and returns the indices for
# the starting and ending integers that, if their elements were sorted, the
# entire array would be sorted.
def unsorted_substring(xs):
ys = xs[:]; ys.sort()
m = 0
while xs[m] == ys[m]:
m += 1
if m >= len(xs):
return -1, -1
n = len(xs) - 1
while xs[n] == ys[n]:
n -= 1
return m, n
print(unsorted_substring([1,2,4,7,10,11,7,12,6,7,16,18,19]))
print(unsorted_substring([1,2,3,4]))
print(unsorted_substring([4,3,2,1]))
print(unsorted_substring([1,3,2,4]))
print(unsorted_substring([2,1,3,4]))
