from math import sqrt if c == '': a = int(a) b = int(b) result = sqrt(a * a + b * b) print(f'The length of side C is: {result}' ) elif b == '': a = int(a) c = int(c) result = sqrt(c * c - a * a) print(f'The length of side B is {result}') elif a == '': b = int(b) c = int(c) result = sqrt((c * c) - (b * b)) print(f'The length of side A is {result}' ) else: print('Please left an empty field to calculate it')