S, M, E and F are working in shifts in a team to finish a project. M works with twice the efficiency of others but for half as many days as E worked. S and M have $6$ hour shifts in a day, whereas E and F have $12$ hours shifts. What is the ratio of contribution of M to contribution of E in the project?
- $1:1$
- $1:2$
- $1:4$
- $2:1$