Buggy python submission (verdict: Time Limit Exceeded):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[1 if i==j else 0 for j in t] for i in s]
    u = [0] * m
    for i in range(n):
        c = a[i]

        for j in range(1,m):
            if c[j] == 1:
                c[j] += u[j-1]

        e = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod

        if i > 0:
            for j in range(m):
                e[j] += u[j]
                e[j] %= mod
        u = e

    r = sum(map(lambda x: sum(x) % mod, a)) + 1

    return r % mod


print(main())





Fixed submission:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[1 if i==j else 0 for j in t] for i in s]
    u = [0] * m
    for i in range(n):
        c = a[i]

        for j in range(1,m):
            if c[j] == 1:
                c[j] += u[j-1]

        e = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod

        if i > 0:
            for j in range(m):
                e[j] += u[j]
                e[j] %= mod
        u = e

    r = sum(map(lambda x: sum(x) % mod, a)) + 1

    return r % mod


print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[0] * m for _ in range(n)]
    u = [[0] * m for _ in range(n)]
    for i in range(n):
        b = s[i]
        c = a[i]
        d = u[i-1]
        for j in range(m):
            if b != t[j]:
                continue
            k = 1
            if i>0 and j>0:
                k += d[j-1]
            c[j] = k
        e = u[i] = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod
        if i > 0:
            for j in range(m):
                e[j] += d[j]
                e[j] %= mod

    r = sum(map(lambda x: sum(x) % mod, a)) + 1
    r %= mod

    return r


print(main())





Fixed submission:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[1 if i==j else 0 for j in t] for i in s]
    u = [0] * m
    for i in range(n):
        c = a[i]

        for j in range(1,m):
            if c[j] == 1:
                c[j] += u[j-1]

        e = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod

        if i > 0:
            for j in range(m):
                e[j] += u[j]
                e[j] %= mod
        u = e

    r = sum(map(lambda x: sum(x) % mod, a)) + 1

    return r % mod


print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[0] * m for _ in range(n)]
    u = [[0] * m for _ in range(n)]
    for i in range(n):
        b = s[i]
        c = a[i]
        d = u[i-1]
        for j in range(m):
            if b != t[j]:
                continue
            k = 1
            if i>0 and j>0:
                k += d[j-1]
            c[j] = k
        e = u[i] = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod
        if i > 0:
            for j in range(m):
                e[j] += d[j]
                e[j] %= mod

    r = sum(map(sum, a)) + 1
    r %= mod

    return r


print(main())





Fixed submission:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[1 if i==j else 0 for j in t] for i in s]
    u = [0] * m
    for i in range(n):
        c = a[i]

        for j in range(1,m):
            if c[j] == 1:
                c[j] += u[j-1]

        e = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod

        if i > 0:
            for j in range(m):
                e[j] += u[j]
                e[j] %= mod
        u = e

    r = sum(map(lambda x: sum(x) % mod, a)) + 1

    return r % mod


print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[0] * m for _ in range(n)]
    u = [[0] * m for _ in range(n)]
    for i in range(n):
        b = s[i]
        c = a[i]
        d = u[i-1]
        for j in range(m):
            if b != t[j]:
                continue
            k = 1
            if i>0 and j>0:
                k += d[j-1]
            c[j] = k
        e = u[i] = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod
        if i > 0:
            for j in range(m):
                e[j] += d[j]
                e[j] %= mod

    r = sum(map(sum, a)) + 1
    r %= mod

    return r


print(main())





Fixed submission:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[1 if i==j else 0 for j in t] for i in s]
    u = [0] * m
    for i in range(n):
        c = a[i]

        for j in range(1,m):
            if c[j] == 1:
                c[j] += u[j-1]

        e = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod

        if i > 0:
            for j in range(m):
                e[j] += u[j]
                e[j] %= mod
        u = e

    r = sum(map(lambda x: sum(x) % mod, a)) + 1

    return r % mod


print(main())

Buggy python submission (verdict: Time Limit Exceeded):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    sc = collections.defaultdict(lambda: collections.defaultdict(int))
    sc[0][(0,0)] = 1
    for i in range(n):
        c = s[i]
        for j in range(i,-1,-1):
            for k,v in sc[j].items():
                nk = ((k[0] * 997 + c) % mod, (k[1] * 991 + c) % mod)
                sc[j+1][nk] += v

    tc = collections.defaultdict(lambda: collections.defaultdict(int))
    tc[0][(0,0)] = 1
    for i in range(m):
        c = t[i]
        for j in range(i,-1,-1):
            for k,v in tc[j].items():
                nk = ((k[0] * 997 + c) % mod, (k[1] * 991 + c) % mod)
                tc[j+1][nk] += v

    r = 0
    for i in range(min(n,m)+1):
        for k,v in tc[i].items():
            r += sc[i][k] * v
            r %= mod

    return r


print(main())





Fixed submission:
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,copy,functools
import time,random

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 10**9+7
mod2 = 998244353
dd = [(-1,0),(0,1),(1,0),(0,-1)]
ddn = [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1),(-1,-1)]

def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(): return [list(map(int, l.split())) for l in sys.stdin.readlines()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)
def pe(s): return print(str(s), file=sys.stderr)
def JA(a, sep): return sep.join(map(str, a))
def JAA(a, s, t): return s.join(t.join(map(str, b)) for b in a)


def main():
    n,m = LI()
    s = LI()
    t = LI()
    a = [[1 if i==j else 0 for j in t] for i in s]
    u = [0] * m
    for i in range(n):
        c = a[i]

        for j in range(1,m):
            if c[j] == 1:
                c[j] += u[j-1]

        e = c[:]
        for j in range(1,m):
            e[j] += e[j-1]
            e[j] %= mod

        if i > 0:
            for j in range(m):
                e[j] += u[j]
                e[j] %= mod
        u = e

    r = sum(map(lambda x: sum(x) % mod, a)) + 1

    return r % mod


print(main())