#include <iostream>
using namespace std;

char ask(int Y){
    cout << "? " << Y << endl;
    char res;
    cin >> res;
    return res;
}

int solve(){
    int askCount = 0;
    for(int i=2;i<=50;i++,askCount++){
        char res = ask(i);
        if(res == '<'){
            return i - 1 + askCount;
        }
        if(res == '='){
            return i + askCount;
        }
    }
    // [lo, hi]
    int lo = 50, hi = 1e9 - askCount;
    for(;;++askCount){
        int mid = (lo + hi) / 2;
        char res = ask(mid);
        if(res == '='){
            return mid + askCount;
        }
        if(res == '<'){
            hi = mid - 1;
        } else {
            lo = mid + 1;
        }
        if(lo == hi){
            return lo + askCount;
        }
        --lo;
        --hi;
    }
    return -1;
}

int main(){
    int Y = solve();
    cout << "! " << Y << endl;
    return 0;
}