There are 47 male Young Pioneers in the first grade of Yongfu Street Primary School, 15 more female Young Pioneers than male Young Pioneers, and the number of fourth grade Young Pioneers is exactly twice that of the first grade. How many young pioneers are there in the fourth grade?
永福街小学一年级有男少先队员47人，女少先队员比男少先队员多15人，四年级少先队员的人数正好是一年级的2倍．四年级有少先队员多少人？
<result>108</result>