Two boxes launched from a spring, find the compression of the spring | Physics 1

Two boxes are at rest with a compressed spring between them. The mass of box 1 is m1, the mass of box 2 is m2. The spring constant is k. The boxes are released and move in opposite directions. Box 1 moves with a velocity of V1 to the left. Assuming there is no air resistance or friction, what is the initial compression of the spring? m1, m2, V1, and k are known values.