import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


enum L = 10^^3;

bool Ask(int x) {
  writefln("? %s", x);
  stdout.flush;
  const res = readToken();
  return (res == "safe");
}

void main() {
  int ans;
  int lo = 0, hi = L + 1;
  for (; hi - lo >= 3; ) {
    const mid = (lo + hi) / 2;
    const res0 = Ask(mid);
    const res1 = Ask(mid + 1);
    if (res0) {
      chmax(ans, mid);
    }
    if (res1) {
      chmax(ans, mid + 1);
    }
    if (res1) {
      lo = mid + 1;
    } else if (res0) {
      lo = mid;
    } else {
      hi = mid;
    }
  }
  foreach (x; lo + 1 .. hi) {
    if (Ask(x)) {
      chmax(ans, x);
    }
  }
  writefln("! %s", ans);
  stdout.flush;
}