n, *a = input().split()
print(sum(i * int(a[i - 1]) for i in range(1, int(n) + 1)))1673A - Subtle Substring Subtraction | 1345A - Puzzle Pieces |
711A - Bus to Udayland | 779B - Weird Rounding |
1703D - Double Strings | 1704C - Virus |
63A - Sinking Ship | 1704B - Luke is a Foodie |
298B - Sail | 239A - Two Bags of Potatoes |
1704E - Count Seconds | 682A - Alyona and Numbers |
44A - Indian Summer | 1133C - Balanced Team |
1704A - Two 0-1 Sequences | 1467A - Wizard of Orz |
1714E - Add Modulo 10 | 1714A - Everyone Loves to Sleep |
764A - Taymyr is calling you | 1714B - Remove Prefix |
1264F - Beautiful Fibonacci Problem | 52A - 123-sequence |
1543A - Exciting Bets | 1714D - Color with Occurrences |
215B - Olympic Medal | 1445A - Array Rearrangment |
1351A - A+B (Trial Problem) | 935B - Fafa and the Gates |
1291A - Even But Not Even | 1269A - Equation |