package main
import (
"fmt"
"math/bits"
)
func main() {
var x uint64
for _, e := fmt.Scanln(&x); e == nil; _, e = fmt.Scanln(&x) {
fmt.Println(bits.Len64(x) - 1)
}
}
Note that non-ascii characters in the above source code will be escaped (such as \x9f).