import re
x = 'beef tomato chicken trump Madonna'
n = 5
right_word = '(?:\s+(\S+))?'
regex_right = r'^\S*{}'.format(n*right_word)
print(regex_right)
m_right = re.search(regex_right, x)
if m_right:
print(m_right.groups())
aW1wb3J0IHJlCnggPSAnYmVlZiB0b21hdG8gY2hpY2tlbiB0cnVtcCBNYWRvbm5hJwpuID0gNQpyaWdodF93b3JkID0gJyg/OlxzKyhcUyspKT8nCnJlZ2V4X3JpZ2h0ID0gcideXFMqe30nLmZvcm1hdChuKnJpZ2h0X3dvcmQpCnByaW50KHJlZ2V4X3JpZ2h0KQptX3JpZ2h0ID0gcmUuc2VhcmNoKHJlZ2V4X3JpZ2h0LCB4KQppZiBtX3JpZ2h0OgoJcHJpbnQobV9yaWdodC5ncm91cHMoKSk=