$\backslash$table$[[$Month# Forecast# Starting inv.#$,$Net requirement#$,$Prod. rate# Ending inv.# Stockout,,,$],[$Jan$,1200,331,869,1120,251,0],[$Feb$,2000,251,1749,1120,0,629],[$Mar$,1000,0,1629,1120,0,509],[$Apr$,230,0,739,1120,381,0],[$May$,1500,381,,1120,1,0]]$

The table above provides the aggregate plan of Remarkable tablet produced by a Norwegian firm. It is known that the firm uses a level plan with backorders. Given this information, what is the number in the cell with $?($If needed, round your final answer to nearest whole number