def edit_distance(string1 , string2):
    n = len(string1)
    m = len(string2)
    dp = []
    for i in range(n+1):
        temp = []
        for j in range(m+1):
            temp.append(0)
        dp.append(temp)

    for i in range(n+1):
        for j in range(m+1):
            if i == 0:
                dp[i][j] = j
            elif j == 0:
                dp[i][j] = i
            elif string1[i-1] == string2[j-1]:
                dp[i][j] = dp[i-1][j-1]
            else:
                dp[i][j] = min(dp[i-1][j-1]+1, dp[i][j-1]+1, dp[i-1][j]+1)

    return dp[n][m]



print(edit_distance("dussehra", "dsusehar"))
print(edit_distance("ihtiha", "ihtas"))
print(edit_distance("cheeks", "checks"))