First there are many ways to approach this problem. The simplest and most direct in my opinion is this approach:
vf^2=v1^2+2ad
so when the height reaches a maximum of 35m the velocity is zero for a split second before starting to fall. So we set vf=0 and solve for v1.
v1=sqrt(2gd)=sqrt(2*9.8*35)= 26.2m/s
for initial velocity needed to reach 35m height.
Any questions please ask!