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A. Possible Subscribers

Input file: standard input

Output file: standard output

Time limit: 1 second

Memory limit: 256 megabytes

MegaMath Channel starts at 0 subscribers. Every day i, the channel gains x_i subscribers. Help MegaMath determine whether this is a possible sequence of values of x_i (the total number of subscribers must stay ≥ 0.)

Input

The first line contains the number of days n (1 <= n <= 100).

The next n lines contain a single integer -10 <= x_i <= 10.

Output

Print "Yes" if the total number of subscribers MegaMath Channel has is, at any given day, >= 0.

Otherwise, print "No".

Sample Code by [blank]: