if side1 == side2:
print("This is an isosceles triangle!")
elif side1 == side3:
print("This is an isosceles triangle!")
elif side2 == side3:
print("This is an isosceles triangle!")
elif side1 != side2 and side1 != side3:
print("This is not an isosceles triangle!")
elif side2 != side1 and side2 != side3:
print("This is not an isosceles triangle!")
elif side3 != side1 and side3 != side2:
print("This is not an isosceles triangle!")