N=5
a=[]
for i in range(N):
  a.append(int(input()))
i=-1
num=a[-1]
f0=f1=1
while f0+f1<num:
  tmp=f1
  f1=f0+tmp
  f0=tmp
if num!=1 and f0+f1!=num:
  print(0)
else:  
  while i-2>=-5 and a[i-2]==a[i-1]+a[i]:
    i-=1
  if i!=-1:
    print(-i+1)
  else:
    print(1)