import sys

n=str(input())
for i in range(len(n)):
    if(i==0):
        if(n[i]!="1"):
            print(-1)
            sys.exit()
            pass;
        pass;
    else:
        if(n[i]!="3"):
            print(-1)
            sys.exit()
            pass;
        pass;
    pass;
if(len(n)==1):
    print(-1)
    pass;
else:
    print(len(n)-1)
    pass;