1+ #!usr/bin/env python3
2+ from collections import defaultdict , deque , Counter , OrderedDict
3+ from bisect import bisect_left , bisect_right
4+ from functools import reduce , lru_cache
5+ from heapq import heappush , heappop , heapify
6+
7+ import itertools
8+ import math , fractions
9+ import sys , copy
10+
11+ def L (): return sys .stdin .readline ().split ()
12+ def I (): return int (sys .stdin .readline ().rstrip ())
13+ def SL (): return list (sys .stdin .readline ().rstrip ())
14+ def LI (): return [int (x ) for x in sys .stdin .readline ().split ()]
15+ def LI1 (): return [int (x ) - 1 for x in sys .stdin .readline ().split ()]
16+ def LS (): return [list (x ) for x in sys .stdin .readline ().split ()]
17+ def R (n ): return [sys .stdin .readline ().strip () for _ in range (n )]
18+ def LR (n ): return [L () for _ in range (n )]
19+ def IR (n ): return [I () for _ in range (n )]
20+ def LIR (n ): return [LI () for _ in range (n )]
21+ def LIR1 (n ): return [LI1 () for _ in range (n )]
22+ def SLR (n ): return [SL () for _ in range (n )]
23+ def LSR (n ): return [LS () for _ in range (n )]
24+
25+ def perm (n , r ): return math .factorial (n ) // math .factorial (r )
26+ def comb (n , r ): return math .factorial (n ) // (math .factorial (r ) * math .factorial (n - r ))
27+
28+ def make_list (n , * args , default = 0 ): return [make_list (* args , default = default ) for _ in range (n )] if args else [default for _ in range (n )]
29+
30+ dire = [[1 , 0 ], [0 , 1 ], [- 1 , 0 ], [0 , - 1 ]]
31+ dire8 = [[1 , 0 ], [1 , 1 ], [0 , 1 ], [- 1 , 1 ], [- 1 , 0 ], [- 1 , - 1 ], [0 , - 1 ], [1 , - 1 ]]
32+ alphabets = "abcdefghijklmnopqrstuvwxyz"
33+ ALPHABETS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
34+ MOD = 1000000007
35+ INF = float ("inf" )
36+
37+ sys .setrecursionlimit (1000000 )
38+
39+ def main ():
40+ N , M = LI ()
41+ F = IR (N )
42+
43+ dp = [0 ] * (N + 1 )
44+ dp [0 ] = 1
45+ d = defaultdict (int )
46+
47+ cum , left = 1 , 0
48+ for right in range (N ):
49+ while d [F [right ]] >= 1 :
50+ d [F [left ]] -= 1
51+ cum = (cum - dp [left ]) % MOD
52+ left += 1
53+ d [F [right ]] += 1
54+ dp [right + 1 ] = cum % MOD
55+ cum = (cum + dp [right + 1 ]) % MOD
56+
57+ print (dp [- 1 ] % MOD )
58+
59+
60+
61+ if __name__ == '__main__' :
62+ main ()
0 commit comments