def ed(s1, s2, m, n):
	dp = [[None for _ in range(n+1)] for _ in range(m+1)]

	for i in range(m+1):
		dp[i][0] = i
	for j in range(n+1):
		dp[0][j] = j
	for i in range(1, m+1):
		for j in range(1, n+1):
			if s1[i-1] == s2[j-1]:
				dp[i][j] = dp[i-1][j-1]
			else:
				dp[i][j] = 1 + min(dp[i-1][j], dp[i][j-1], dp[i-1][j-1])

	return dp[m][n]

print(ed("SATURDAY", "SUNDAY", 8, 6))				
