import std;
void main() {
	int ok = cast(int)1e9, ng = 0;
    while(abs(ok - ng) > 1) {
    	const x = (ok + ng) / 2;
    	writeln(x);
    	const r = readln.chomp.to!int;
    	assert(r != -1);
    	if(r == 1) {
    		return;
    	}
    	ok = x;
    }
}