#P3131. [USACO16JAN] Subsequences Summing to Sevens S

[USACO16JAN] Subsequences Summing to Sevens S

Description

Farmer John's NN cows are standing in a row, as they have a tendency to do from time to time. Each cow is labeled with a distinct integer ID number so FJ can tell them apart. FJ would like to take a photo of a contiguous group of cows but, due to a traumatic childhood incident involving the numbers 161 \ldots 6, he only wants to take a picture of a group of cows if their IDs add up to a multiple of 7.

Please help FJ determine the size of the largest group he can photograph.

Input Format

The first line of input contains NN (1N50,0001 \leq N \leq 50,000). The next NN lines each contain the NN integer IDs of the cows (all are in the range 01,000,0000 \ldots 1,000,000).

Output Format

Please output the number of cows in the largest consecutive group whose IDs sum to a multiple of 7. If no such group exists, output 0.

7
3
5
1
6
2
14
10
5

Hint

In this example, 5+1+6+2+14=285+1+6+2+14 = 28.