n, *a = input().split()
print(sum(i * int(a[i - 1]) for i in range(1, int(n) + 1)))67B - Restoration of the Permutation | 1734A - Select Three Sticks |
1734B - Bright Nice Brilliant | 357B - Flag Day |
937A - Olympiad | 1075A - The King's Race |
1734C - Removing Smallest Multiples | 1004C - Sonya and Robots |
922A - Cloning Toys | 817A - Treasure Hunt |
1136B - Nastya Is Playing Computer Games | 1388A - Captain Flint and Crew Recruitment |
592B - The Monster and the Squirrel | 1081A - Definite Game |
721C - Journey | 1400A - String Similarity |
1734E - Rectangular Congruence | 1312D - Count the Arrays |
424C - Magic Formulas | 1730C - Minimum Notation |
1730B - Meeting on the Line | 1730A - Planets |
302B - Eugeny and Play List | 1730D - Prefixes and Suffixes |
1515C - Phoenix and Towers | 998A - Balloons |
1734F - Zeros and Ones | 1144B - Parity Alternated Deletions |
92B - Binary Number | 1144C - Two Shuffled Sequences |