d=list(map(int,input().split(",")))
key=int(input())
f=False
i = 0
j = len(d) - 1
while __________:
    m = (i+j) //2
    if d[m] == key:           
        f=True
    if key < d[m]:            
        j = m - 1
    else:                    
        __________
if f==True:
    print(m)
else:
    print(-1)