import Foundation 

let s = readLine()!
if s.count <= 1 {
    print(-1)
    exit(0)    
}

if s.prefix(1) != "1" {
    print(-1)
    exit(0)    
}

if s.suffix(s.count - 1).first(where: { $0 != "3" }) != nil {
    print(-1)
    exit(0)    
} 

print(s.count - 1)