| m % 10 = n % 10, n→s(m % 10) = n→s(n % 10), m / 10 = n / 10, 10 ≤ n, 10 ≤ m, ∀ m1, n. m1 < m → n→s(m1) = n→s(n) → m1 = n ⊦ n = 0, m = 0, m = n |
m / 10 = n / 10, m % 10 = n % 10, 10 ≤ m, 10 ≤ n, ∀ m1, n. m1 < m → n→s(m1) = n→s(n) → m1 = n ⊦ m = n, m = 0, n = 0