package main

import (
    "fmt"
    "math/big"
)

func main() {
    x := big.NewInt(1)
    one := big.NewInt(1)

    n := 0
    for {
        x.Mul(x, x).Add(x, one)
        n++

        if x.BitLen() > 70000 {
            break
        }
    }
    fmt.Println(n)
}