# assign max_sum with the greater of num_a and num_b PLUS the greater of num_y and num_z. Use just one statement. 
# Hint: Call find_max() twice in an expression

def find_max(num_1, num_2): 
    max_val = 0.0 

    if (num_1 > num_2): # if num1 is greater than num2 
        max_val = num_1 # then num1 is the maxVal
    else: 
        max_val = num_2 
    return max_val 

max_sum = 0.0 
num_a = float(input())
num_b = float(input())
num_y = float(input())
num_z = float(input())

max_sum = find_max(num_a, num_b) + find_max(num_y, num_z)