Depth Log Surface Crossings

A diver begins a dive exactly at the surface, which is treated as depth 0. Over the course of the dive, the dive computer records n consecutive depth-change readings in chronological order. The i-th reading is a nonzero signed integer: a positive value means the diver descended (moved deeper) by that many meters since the previous reading, and a negative value means the diver ascended (moved toward the surface) by that many meters.

After each reading, the diver's cumulative depth is the sum of all readings so far. Count how many of the n readings leave the diver's cumulative depth exactly equal to 0 (i.e. exactly back at the surface) at that moment. The very start of the dive, before any readings are taken, is also at depth 0 but must not be counted.

Input format

Line 1: a single integer n, the number of readings. Line 2: n space-separated nonzero integers -- the depth-change readings, in chronological order.

Output format

Print a single integer: the number of readings after which the cumulative depth is exactly 0.

Constraints

• 1 <= n <= 100000
• -10000 <= each reading <= 10000, and no reading is 0.

5
2 3 -5 5 -3

1

3
3 2 -3

0