# Generate the Fibonacci list up to a sufficiently large number
fib = [1, 1]
while True:
    next_val = fib[-1] + fib[-2]
    fib.append(next_val)
    if next_val > 10**18:
        break

# Read input and reverse it to process from the bottom up
s = [int(input()) for _ in range(5)][::-1]

max_n = 0

# Check from n=5 down to n=1
for n in range(5, 0, -1):
    sub = s[:n]
    
    # Check non-decreasing
    valid_non_decreasing = True
    for i in range(len(sub) - 1):
        if sub[i] > sub[i + 1]:
            valid_non_decreasing = False
            break
    if not valid_non_decreasing:
        continue
    
    # Check Fibonacci conditions
    if len(sub) == 1:
        # Check if the single element is a Fibonacci number
        if sub[0] in fib:
            max_n = n
            break
    else:
        a, b = sub[0], sub[1]
        # Check if a and b are consecutive Fibonacci numbers
        found = False
        for i in range(len(fib) - 1):
            if fib[i] == a and fib[i + 1] == b:
                found = True
                break
        if not found:
            continue
        
        # Check subsequent elements follow the Fibonacci rule
        valid_rest = True
        for i in range(2, len(sub)):
            if sub[i] != sub[i - 1] + sub[i - 2]:
                valid_rest = False
                break
        if valid_rest:
            max_n = n
            break

print(max_n)