Is the 1500 calorie diet too much to loose weight?

i really wanted to loose much weight for this month. and i am really determined to exercise. maybe 30 minutes stair climbing and maybe 5 to 15 minutes cycling (because for some reason, i can't last long in cycling). i wanted to loose about 10 to 15 kilos this month. i know its hard, but for the regimen i showed, should i increase my exercise or decrease my calorie intake?