package main

import (
	"fmt"
)

func main() {
	var n int
	fmt.Scan(&n)

	L, R := 1, n-1
	for L < R {
		M := (L + R + 1) / 2
		base := (L/n + 1) * n
		c := base - M
		fmt.Printf("+ %d\n", c)
		var k int
		fmt.Scan(&k)
		L += c
		R += c
		if L < k*n {
			L = k * n
		}
		if R > k*n+n-1 {
			R = k*n + n - 1
		}
	}
	fmt.Printf("! %d\n", L)
}