Melting ice - how many photons?

[mss90]

Homework Statement

how many photons (lambda=620*10^-9) must be absorbed to melt 2kg block of ice at 0deg into water at 0deg? and on average, how many H2O molecules does one photon convert from the ice phase to water phase?

Homework Equations

E=hc/lambda

The Attempt at a Solution

I have no idea how to do this? Never done anything like it before!
Any hints?

 

[TSny]

Recall your first semester physics where you learned how to find the heat required to melt ice. The energy of the photons absorbed by the ice can be considered as equivalent to the required heat.