import sys

x = 0

y = 1000

while x < y:
    
    
    z = (x + y) // 2
    
    print('?', z)
    
    if input() == 'safe':
        
        sys.stdout.flush()
        
        x = z
        continue
    
    sys.stdout.flush()
    
    print('?', z + 1)
    
    if input() == 'safe':
        
        x = z + 1
    else:
        
        y = z - 1
        
    sys.stdout.flush()
    
print('!', x)