From blocks 300.000 to blocks 400.000, block rewards are 50 coins/ block; then total coins for those 100.000 blocks will be equaled 50x100.000 = 500.000 coins.
You should replaced those total number of blocks, and block rewards for each phase, calculate total number of coins will be release each phase
Then sum up all of them, you will get what you want.
Good luck.