fn main() { let mut n = String::new(); std::io::stdin().read_line(&mut n).ok(); let n: isize = n.trim().parse().unwrap(); let mut upper = n-1; let mut lower = 1isize; println!("? {}", lower); let mut sl = String::new(); std::io::stdin().read_line(&mut sl).ok(); let sl: isize = sl.trim().parse().unwrap(); let sl = sl * 2 - 1; println!("? {}", upper); let mut sr = String::new(); std::io::stdin().read_line(&mut sr).ok(); let sr: isize = sr.trim().parse().unwrap(); let sr = sr * 2 - (n - 1); if sl == sr { println!("! {} {}", lower+1, upper); return; } let pm = -sl; while lower < upper { let middle = (upper + lower) / 2; println!("? {}", middle); let mut sl = String::new(); std::io::stdin().read_line(&mut sl).ok(); let sl: isize = sl.trim().parse().unwrap(); let sl = sl * 2 - middle; if sl == 0 { lower = middle; upper = middle; } else if sl * pm < 0 { lower = middle; } else { upper = middle; } } if lower >= n/2 { println!("! {} {}", 1, lower); } else { println!("! {} {}", lower+1, n); } }