Harryxun/sft_time huggingface dataset:
### BUGGY CODE ###

s = input()
K = int(input())
d = []
ele = []
for i in range(len(s)):
    if not s[i] in d:
        d.append(s[i])
    ele = []
    ele.append(s[i])
    for j in range(i+1,len(s)):
        ele.append(s[j])
        if not ''.join(ele) in d:
            d.append(''.join(ele))
d.sort()
print(d[K-1])


### FIXED CODE ###

s = input()
K = int(input())
d = []
ele = []
for i in range(len(s)):
    for j in range(0,K):
        substr = s[i:i+j+1]
        if not substr in d and len(substr)<=K:
            d.append(substr)
d.sort()
print(d[K-1])
### BUGGY CODE ###

n = int(input())
a = list(map(int, input().split()))

ans = 1
for i in a:
    ans = ans*i

if ans <= 1000000000000000000:
	print(ans)
else:
  	print(-1)

### FIXED CODE ###

n = int(input())
a = list(map(int, input().split()))

ans = 1
for i in a:
    if i == 0:
      	ans = 0

if ans != 0:
	for i in a:
		ans = ans*i
		if ans > 1000000000000000000:
			break

if ans <= 1000000000000000000:
	print(ans)
else:
  	print(-1)
### BUGGY CODE ###

import math
a,b,n = map(int, input().split())

ans = 0
lenge = min(b-1, n)
for x in range(lenge+1):
    y = math.floor((a*x)/b) - a * math.floor(x/b)
    ans = max(y, ans)

print(ans)

### FIXED CODE ###

a,b,n=map(int,input().split())
x=min(b-1,n)
print((a*x)//b-a*(x//b))
### BUGGY CODE ###

from scipy.sparse import csr_matrix
from scipy.sparse.csgraph import dijkstra

#nodes will be (steps % 3) * N + node

N, M = map(int, input().split())
start = []
goal = []
for _ in range(M):
    u, v = map(int, input().split())
    u -= 1
    v -= 1

    start.append(u)
    goal.append(N + v)

    start.append(N + u)
    goal.append(2*N + v)

    start.append(2*N + u)
    goal.append(v)

S, T = map(int, input().split())
    

cost = [1] * len(start)
digraph = csr_matrix((cost, (start, goal)), (3*N, 3*N))
ans = dijkstra(digraph, unweighted = True, indices = S-1)[T-1]
if ans == float("inf"):
    print(-1)
else:
    print(int(ans) // 3)

### FIXED CODE ###

from collections import deque

#create digraph
#nodes will be (steps % 3) * N + node
N, M = map(int, input().split())
adj = [[] for _ in range(3*N)]
for _ in range(M):
    u, v = map(int, input().split())
    u -= 1
    v -= 1

    adj[      u].append(  N + v)
    adj[  N + u].append(2*N + v)
    adj[2*N + u].append(      v)

S, T = map(int, input().split())
S -= 1
T -= 1

#bfs
q = deque([S])
depth = [10 ** 9] * (3*N)
depth[S] = 0
while q:
    node = q.popleft()
    if node == T:
        break
    for next_node in adj[node]:
        if depth[next_node] > depth[node] + 1:
            depth[next_node] = depth[node] + 1
            q.append(next_node)

if depth[T] == 10 ** 9:
    print(-1)
else:
    print(depth[T] // 3)
### BUGGY CODE ###

# -*- coding: utf-8 -*-
"""
Created on Sun Mar 17 09:02:00 2019
DPF3
@author: maezawa
"""

s = input()
t = input()

ns = len(s)
nt = len(t)

dp = [[0 for _ in range(nt+1)] for _ in range(ns+1)]

for si in range(ns):
    for ti in range(nt):
        if s[si] == t[ti]:
            dp[si+1][ti+1] = max(dp[si][ti]+1, dp[si+1][ti], dp[si][ti+1])
        else:
            dp[si+1][ti+1] = max(dp[si+1][ti], dp[si][ti+1])

ans = ''
si = ns
ti = nt
while si > 0 and ti > 0:
    if dp[si][ti] == dp[si-1][ti]: 
        si -= 1
    elif dp[si][ti] == dp[si][ti-1]:
        ti -= 1
    else:
        ans = s[si-1] + ans
        si -= 1
        ti -= 1

print(ans)



### FIXED CODE ###

# -*- coding: utf-8 -*-
"""
Created on Sun Mar 17 09:02:00 2019
DPF3
@author: maezawa
"""

s = input()
t = input()

ns = len(s)
nt = len(t)

dp = [[0 for _ in range(nt+1)] for _ in range(ns+1)]

for si in range(ns):
    for ti in range(nt):
        if s[si] == t[ti]:
            dp[si+1][ti+1] = max(dp[si][ti]+1, dp[si+1][ti], dp[si][ti+1])
        else:
            dp[si+1][ti+1] = max(dp[si+1][ti], dp[si][ti+1])

ans = ''
si = ns
ti = nt
while si > 0 and ti > 0:
    if dp[si][ti] == dp[si-1][ti]: 
        si -= 1
    elif dp[si][ti] == dp[si][ti-1]:
        ti -= 1
    else:
        ans = s[si-1] + ans
        si -= 1
        ti -= 1

print(ans)
### BUGGY CODE ###

import math
def primes(n):
    ass = []
    is_prime = [True] * (n + 1)
    is_prime[0] = False
    is_prime[1] = False
    for i in range(2, int(n ** 0.5) + 1):
        if not is_prime[i]:
            continue
        for j in range(i * 2, n + 1, i):
            is_prime[j] = False
    for i in range(len(is_prime)):
        if is_prime[i]:
            ass.append(i)
    return ass

def divisor(n):
    ass = []
    for i in range(1, int(n ** 0.5) + 1):
        if n % i == 0:
            if i != 1:
                ass.append(i)
            if i ** 2 == n:
                continue
            ass.append(n // i)
    return ass

n = int(input())
a = list(map(int, input().split()))
pair = False
divisors = set(divisor(a[0]))
ggcd = a[0]
for i in range(1, n):
    divs = set(divisor(a[i]))
    if len(divs & divisors) != 0:
        pair = True
    else:
        divisors = set(list(divisors) + list(divs))
    ggcd = math.gcd(ggcd, a[i])
if ggcd != 1:
    print("not coprime")
else:
    if pair:
        print("setwise coprime")
    else:
        print("pairwise coprime")

### FIXED CODE ###

def resolve():
    import math
    n = int(input())
    a = list(set(map(int, input().split())))
    maxa = max(a)

    ggcd = a[0]
    for i in range(1, len(a)):
        ggcd = math.gcd(ggcd, a[i])
        if ggcd == 1:
            break

    pair = False

    c = [0] * (10**6+ 1)
    for i in a:
        c[i] += 1

    for i in range(2, maxa+1):
        cnt = 0
        for j in range(i, maxa+1, i):

            cnt += c[j]
        if cnt > 1:
            pair = True

    if ggcd != 1:
        print("not coprime")
    else:
        if pair:
            print("setwise coprime")
        else:
            print("pairwise coprime")
resolve()
### BUGGY CODE ###

#!/usr/bin/env python3
#%% for atcoder uniittest use
import sys
input= lambda: sys.stdin.readline().rstrip()
def pin(type=int):return map(type,input().split())
def tupin(t=int):return tuple(pin(t))
#%%code
import random
def resolve():
    A,B,N=pin()
    def f(A,B,x):
        t=(A*x)//B
        s=x//B
        return t-A*s
    ans=0
    for i in range(10**7):
        k=random.randint(0,N)
        ans=max(ans,f(A,B,k))
    print(ans)
#%%submit!
resolve()

### FIXED CODE ###

#!/usr/bin/env python3
#%% for atcoder uniittest use
import sys
input= lambda: sys.stdin.readline().rstrip()
def pin(type=int):return map(type,input().split())
def tupin(t=int):return tuple(pin(t))
#%%code
import random
def resolve():
    A,B,N=pin()
    def f(A,B,x):
        t=(A*x)//B
        s=x//B
        return t-A*s
    ans=0
    for i in range(10**6):
        k=random.randint(0,N)
        ans=max(ans,f(A,B,k))
    print(ans)
#%%submit!
resolve()
### BUGGY CODE ###

#!/usr/bin/env python3
from itertools import permutations
import sys
try:
    from typing import List
except ImportError:
    pass


def solve(N: int, M: int, R: int, r: "List[int]", A: "List[int]", B: "List[int]", C: "List[int]"):
    inf = float("inf")
    md = [[inf] * N for _ in range(N)]
    for i in range(N):
        md[i][i] = 0
    for Ai, Bi, Ci in zip(A, B, C):
        Ai -= 1
        Bi -= 1
        md[Ai][Bi] = md[Bi][Ai] = Ci
    for k in range(N):
        for i in range(N):
            for j in range(N):
                md[i][j] = min(md[i][j], md[i][k] + md[k][j])

    def dist(path):
        return sum(md[p1 - 1][p2 - 1] for p1, p2 in zip(path, path[1:]))

    print(min(dist(path) for path in permutations(r)))


def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    R = int(next(tokens))  # type: int
    r = [int(next(tokens)) for _ in range(R)]  # type: "List[int]"
    A = [int()] * (M)  # type: "List[int]"
    B = [int()] * (M)  # type: "List[int]"
    C = [int()] * (M)  # type: "List[int]"
    for i in range(M):
        A[i] = int(next(tokens))
        B[i] = int(next(tokens))
        C[i] = int(next(tokens))
    solve(N, M, R, r, A, B, C)


if __name__ == '__main__':
    main()


### FIXED CODE ###

#!/usr/bin/env python3
from itertools import permutations
import sys
try:
    from typing import List
except ImportError:
    pass


def solve(N: int, M: int, R: int, r: "List[int]", A: "List[int]", B: "List[int]", C: "List[int]"):
    inf = float("inf")
    md = [[inf] * N for _ in range(N)]
    for i in range(N):
        md[i][i] = 0
    for Ai, Bi, Ci in zip(A, B, C):
        Ai -= 1
        Bi -= 1
        md[Ai][Bi] = md[Bi][Ai] = Ci
    for k in range(N):
        for i in range(N):
            for j in range(N):
                md[i][j] = min(md[i][j], md[i][k] + md[k][j])

    def dist(path):
        return sum(md[p1 - 1][p2 - 1] for p1, p2 in zip(path, path[1:]))

    print(min(dist(path) for path in permutations(r)))


def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    R = int(next(tokens))  # type: int
    r = [int(next(tokens)) for _ in range(R)]  # type: "List[int]"
    A = [int()] * (M)  # type: "List[int]"
    B = [int()] * (M)  # type: "List[int]"
    C = [int()] * (M)  # type: "List[int]"
    for i in range(M):
        A[i] = int(next(tokens))
        B[i] = int(next(tokens))
        C[i] = int(next(tokens))
    solve(N, M, R, r, A, B, C)


if __name__ == '__main__':
    main()
### BUGGY CODE ###

N, M, Q = map(int, input().split())
lis = []
for i in range(Q):
    a = list(map(int, input().split()))
    lis.append(a)


big_lis = []


def dfs(string, n, m):
    if n == (N - 1):
        for i in range(m, M + 1):
            big_lis.append(string + [i])
    else:
        for i in range(m, M + 1):
            dfs(string + [i], n + 1, i)


dfs([], 0, 1)

MAX_A = 0
for small_lis in big_lis:
    D = 0
    for j in range(Q):
        if small_lis[int(lis[j][1]) - 1] - small_lis[int(lis[j][0]) - 1] == int(lis[j][2]):
            D += int(lis[j][3])
    MAX_A = max(MAX_A, D)
print(MAX_A)


### FIXED CODE ###

N, M, Q = map(int, input().split())
lis = []
for i in range(Q):
    a = list(map(int, input().split()))
    lis.append(a)


big_lis = []


def dfs(string, n, m):
    if n == (N - 1):
        for i in range(m, M + 1):
            big_lis.append(string + [i])
    else:
        for i in range(m, M + 1):
            dfs(string + [i], n + 1, i)


dfs([], 0, 1)

MAX_A = 0
for small_lis in big_lis:
    D = 0
    for j in range(Q):
        if small_lis[int(lis[j][1]) - 1] - small_lis[int(lis[j][0]) - 1] == int(lis[j][2]):
            D += int(lis[j][3])
    MAX_A = max(MAX_A, D)
print(MAX_A)
### BUGGY CODE ###

# coding:utf-8

import copy

Black = "#"
White = "."

dir_x = [1, 0, -1, 0]
dir_y = [0, 1, 0, -1]


def main():
    H, W = map(int, input().split())
    masu = []
    step = 0
    count = W*H
    memo = [[-1]*W for i in range(H)]
    steplist = []

    # for i in range(H):
    #     masu.append(input().rstrip())

    for y in range(H):
        temp_in = input()
        for x in range(W):
            if temp_in[x] == Black:
                memo[y][x] = 0
                count -= 1
                steplist.append([y, x])

    while count > 0:
        step += 1
        next_list = []
        for l in steplist:
            y = l[0]
            x = l[1]
            for i in range(4):
                temp_x = x + dir_x[i]
                temp_y = y + dir_y[i]
                if temp_x >= 0 and temp_x < W and temp_y >= 0 and temp_y < H and memo[temp_y][temp_x] < 0:
                    memo[temp_y][temp_x] = step
                    count -= 1
                    next_list.append([temp_y, temp_x])
        steplist = next_list
    print(step)


if __name__ == "__main__":
    main()


### FIXED CODE ###

# coding:utf-8

Black = "#"
White = "."

dir_x = [1, 0, -1, 0]
dir_y = [0, 1, 0, -1]


def main():
    H, W = map(int, input().split())
    step = 0
    count = W*H
    memo = [[-1]*W for i in range(H)]
    steplist = []

    for y in range(H):
        temp_in = input()
        for x in range(W):
            if temp_in[x] == Black:
                memo[y][x] = 0
                count -= 1
                steplist.append([y, x])

    while count > 0:
        step += 1
        next_list = []
        for l_yx in steplist:
            for i in range(4):
                temp_x = l_yx[1] + dir_x[i]
                temp_y = l_yx[0] + dir_y[i]
                if temp_x >= 0 and temp_x < W and temp_y >= 0 and temp_y < H:
                    if memo[temp_y][temp_x] < 0:
                        memo[temp_y][temp_x] = step
                        count -= 1
                        next_list.append([temp_y, temp_x])
        steplist = next_list
    print(step)


if __name__ == "__main__":
    main()
### BUGGY CODE ###

A, B, C, D = map(int, input().split())

counter = 0

for n in range(B-A+1):
  if (A + n) %C !=0 and (A+n)% D != 0:
    counter += 1

print(counter)

### FIXED CODE ###

A, B, C, D = map(int, input().split())

CSeries = B//C -(A-1)//C
DSeries = B //D - (A-1) //D

def gcd(a,b):
  while b!=0:
    a,b=b,a%b
  return a

LCM = int(C*D/ gcd(C,D))

CDSeries = B//LCM - (A-1)//LCM

Answer2 = B-A +1 - CSeries - DSeries + CDSeries

print(Answer2)
### BUGGY CODE ###


N = int(input())
S = input()
cnt = 0
for i in range(1000):
    C = [str(i//100), str(i//10%10), str(i%10)]
    f = 0
    for s in S:
        if s == C[f]:
            f += 1
        if f == 3:
           break
    if f == 3:
        cnt += 1
    if cnt ==1000:
        break
print(cnt)


### FIXED CODE ###

# sumitb2019_d.py
'''
重複考えないとどうなるか
-> 単に nC3 個( N 個から 3 つ選び出す順列と同じ)
というところまで考えたが、結局わからず解説AC
重複を考えるとかなり厳しいので重複がないものに着目する。
（今回であれば 000~999 までのパスワード）
発想の転換が凄い。これ思いつくの天才だろ…。
'''
N = int(input())
S = input()
cnt = 0
for i in range(1000):
    C = [str(i//100), str(i//10%10), str(i%10)]
    f = 0
    for s in S:
        if s == C[f]:
            f += 1
        if f == 3:
           break
    if f == 3:
        cnt += 1
    if cnt ==1000:
        break
print(cnt)
### BUGGY CODE ###

n = int(input())
s = input()

an = s.count('R') *s.count('G') *s.count('B')

for i in range(n-2):
    for j in range(i+1,n-1):
        for k in range(j+1,n):
            if ((i-j)==(j-k)) and (s[i]!=s[j]) and (s[j]!=s[k])and(s[i]!=s[k]):
                an -= 1

print(an)

### FIXED CODE ###

n = int(input())
s = input()

an = s.count('R') *s.count('G') *s.count('B')

for i in range(n-2):
    for j in range(i+1,n-1):
        k = 2*j-i
        if (k<n) and (s[i]!=s[j]) and (s[j]!=s[k])and(s[i]!=s[k]):
                an -= 1

print(an)
### BUGGY CODE ###

N = int(input())
Ps = list(map(int, input().split()))
count = 0
low = -1

for i in range(N):
    low = Ps[i]

    for j in range(i):
        if (low > Ps[j]):
            break
        if (low > Ps[i-1-j]):
            break
        if (low > Ps[i-1//2-j]):
            break
        if (j == i-1):
            count += 1

print(count+1)

### FIXED CODE ###

N = int(input())
Ps = list(map(int, input().split()))
count = 0
min = Ps[0]+1

for i in range(N):
    if (Ps[i] < min):
        min = Ps[i]
        count += 1

print(count)
### BUGGY CODE ###

n, a, b = map(int, input().split())
mod = pow(10, 9) + 7
total = pow(2, n) - 1

def comb(N, x):
    numerator = 1
    for i in range(N-x+1, N+1):
        numerator = numerator * i % mod
    denominator = 1
    for j in range(1, x+1):
        denominator = denominator * j % mod
    d = pow(denominator, mod-2, mod)
    return numerator * d

a = comb(n, a)
b = comb(n, b)

print((total -a -b) % mod)

### FIXED CODE ###

n, a, b = map(int, input().split())
mod = pow(10, 9) + 7

def comb(N, x):
    numerator = 1
    for i in range(N-x+1, N+1):
        numerator = numerator * i % mod
    denominator = 1
    for j in range(1, x+1):
        denominator = denominator * j % mod
    d = pow(denominator, mod-2, mod)
    return numerator * d

a = comb(n, a)
b = comb(n, b)

print((pow(2, n, mod) -1 -a -b) % mod)
### BUGGY CODE ###

from copy import copy

n = int(input())
x = list(map(int,input().split()))

x_sorted = sorted(x)

for i in range(n):
    l = x_sorted.copy()
    l.remove(x[i])
    print(l[int(n/2)-1])



### FIXED CODE ###

n = int(input())
x = list(map(int,input().split()))

x_sorted = sorted(x)

med = (x_sorted[int(n/2)-1] + x_sorted[int(n/2)])/2

for i in range(n):
    if x[i]<med:
        print(x_sorted[int(n/2)])
    else:
        print(x_sorted[int(n/2)-1])
### BUGGY CODE ###

from itertools import combinations
import copy
N=int(input())
A=list(map(int,input().split()))
B=[0]*N
for i in A:
   B[i-1]+=1 
def X (k):
    c=0
    C=copy.deepcopy(B)
    C[k-1]-=1
    for i in range(N):
        if C[i-1]>=2:
            c+=len(list(combinations(range(C[i-1]),2)))
    return c
for j in A:
    print(X(j))

### FIXED CODE ###

N=int(input())
A=list(map(int,input().split()))
B=[0]*(N+1)
C=0
for i in A:
    B[i-1]+=1
for i in B:
    if i>=2:
        C+=i*(i-1)//2
for i in A:
    print(C-B[i-1]+1)
### BUGGY CODE ###

n, q = map(int, input().split())
s = input()
g = [1 for _ in range(n)]
for _ in range(q):
    t, d = input().split()
    for i in range(n):
        if s[i] == t:
            if d == 'L':
                if i != 0:
                    g[i-1] += g[i]
            else:
                if i != n-1:
                    g[i+1] += g[i]
            g[i] = 0
print(sum(g))

### FIXED CODE ###

import sys
def vanish_on_left(i, n, s, tds):
    for t, d in tds:
        if s[i] != t:
            continue
        if d == 'L':
            if i == 0:
                return True
            i -= 1
        else:
            if i == n-1:
                return False
            i += 1
    return False

def vanish_on_right(i, n, s, tds):
    for t, d in tds:
        if s[i] != t:
            continue
        if d == 'L':
            if i == 0:
                return False 
            i -= 1
        else:
            if i == n-1:
                return True
            i += 1
    return False


n, q = map(int, input().split())
s = input()
tds = []
for _ in range(q):
    tds.append(tuple(input().split()))
if vanish_on_left(0, n, s, tds):
    if vanish_on_left(n-1, n, s, tds):
        print(0)
        sys.exit()
    l0, r0 = 1, n-1
    while l0 < r0:
        k = (l0 + r0) // 2
        if vanish_on_left(k, n, s, tds):
            l0 = k+1
        else:
            r0 = k
else:
    l0 = 0
if vanish_on_right(n-1, n, s, tds):
    if vanish_on_right(l0, n, s, tds):
        print(0)
        sys.exit()
    l1, r1 = l0, n-2
    while l1 < r1:
        k = (l1 + r1 + 1) // 2
        if vanish_on_right(k, n, s, tds):
            r1 = k-1
        else:
            l1 = k
else:
    l1 = n-1
print(l1 - l0 + 1)
### BUGGY CODE ###

n = int(input())
a = list(map(int, input().split()))
d = {}

for i in range(n):
    if a[i] in d:
        d[a[i]] += 1
    else:
        d[a[i]] = 1

for i in range(n):
    b = a[i]
    d[b] = d[b]-1
    count = 0
    for j in d:
        temp_count = d[j]*(d[j]-1)//2
        count += temp_count
    d[b] = d[b] + 1
    print(count)


### FIXED CODE ###

n = int(input())
a = list(map(int, input().split()))
d = {}

for i in range(n):
    if a[i] in d:
        d[a[i]] += 1
    else:
        d[a[i]] = 1

count = 0
for i in d:
    count += d[i] * (d[i] - 1) // 2


for i in range(n):
    b = d[a[i]]
    print(count-b+1)
### BUGGY CODE ###

from collections import Counter
from scipy.misc import comb
N = int(input())
A = input().split()
C = Counter(A)
def banned_count(seq):
    for i in range(N):
        count = 0
        C[A[i]] -= 1
        for j in C.values():
            if j >= 2:
                count += comb(j, 2, exact=True)
        print(count)
        C[A[i]] += 1
banned_count(A)

### FIXED CODE ###

from collections import Counter
from scipy.misc import comb
N = int(input())
A = input().split()
C = Counter(A)
s = sum([comb(j, 2, exact=True) for j in C.values()])
for i in range(N):
    print(s-C[A[i]]+1)
### BUGGY CODE ###


s=input()
s= s[::-1]

S=[0,]

for n,i in enumerate(s):
    # print(s[n], i, n)
    S.append((int(S[n]) + int(i) * 10**n) % 2019)

# print(S)
ans=0
for i in range(0,len(s)-4):
    for j in range(i+5, len(s)+1):
        if S[i]- S[j]==0:
            ans+=1

print(ans)

### FIXED CODE ###

s=input()
s= s[::-1]

S=[0,]
cnt=[0]*2019
cnt[0]=1
d=1
num=0
for i in range(len(s)):
    num += int(s[i])*d
    num %= 2019
    d *= 10
    d%= 2019
    # S.append((int(S[i]) + int(s[i]) * 10**i) % 2019)
    cnt[num]+=1

ans=0
for i in cnt:
    ans += i*(i-1) //2

print(ans)
### BUGGY CODE ###

import numpy as np
H,N=map(int,list(input().split(" ")))
magic=[]
power=[]
for i in range(N):
    A,B=map(int,list(input().split(" ")))
    magic+=[A]
    power+=[B]
dp=[[np.inf for i in range(2*H+1)] for j in range(N+1)]
for i in range(N+1):
    dp[i][0]=0
ma=[]
for j in range(1,2*H+1):
    for i in range(1,N+1):
        if j-magic[i-1]>=0:
            dp[i][j]=min(dp[i-1][j],dp[i][j-magic[i-1]]+power[i-1])
        else:
            dp[i][j]=min(dp[i-1][j],power[i-1])
print(dp[N][H])

### FIXED CODE ###

import numpy as np
H,N=map(int,list(input().split(" ")))
a=np.empty(N,dtype=int)
b=np.empty(N,dtype=int)
for i in range(N):
    a[i],b[i]=map(int,list(input().split(" ")))
dp=np.empty(H+1,dtype=int)
dp[0]=0
for h in range(1,H+1):
    t=h-a
    t[t<0]=0
    dp[h]=np.min(dp[t]+b)
print(dp[H])
### BUGGY CODE ###

h, w, n = map(int, input().split())
wall = [list(map(int, input().split())) for _ in range(n)]

wall.sort(key=lambda x: x[1])
wall.sort(key=lambda x: x[0])


# combination---

mod = 10**9 + 7
fac = [1, 1]
inv = [1, 1]
finv = [1, 1]
for i in range(2, h+w+1):
    fac.append(fac[i-1] * i % mod)
    inv.append(mod - inv[mod%i] * (mod//i) % mod)
    finv.append(finv[i-1] * inv[i] % mod)

def nck(n, k):
    if n < k:
        return 0
    if n < 0 or k < 0:
        return 0
    return fac[n] * (finv[k] * finv[n-k] % mod) % mod



# dp[i]:= i-1番目までの壁を通らず、i番目の壁にたどり着く経路の数
dp = [0] * n

for i in range(n):
    res = 0    # i-1までの壁を一回以上通って、i回目の壁にたどり着く経路数
    for j in range(i):
        # 最初にぶつかる壁がjで、iの壁に到達する経路数を求めていく
        res += dp[j] * nck(wall[i][0] - wall[j][0] + wall[i][1] - wall[j][1], wall[i][0] - wall[j][0])
        res %= mod
        
    # dp[i] = (i番目の壁までの経路数) - (i-1までの壁を一回以上通って、i回目の壁にたどり着く経路数)
    dp[i] = nck(wall[i][0] - 1 + wall[i][1] - 1, wall[i][0] - 1) - res
    dp[i] %= mod

# 余事象 ((h, w)までに少なくとも1つの壁にぶつかる経路数を数える)
ans = 0
for i in range(n):
    # 最初にぶつかる壁がiで、(h, w)に到達する経路数
    ans += dp[i] * nck(h - wall[i][0] + w - wall[i][1], h - wall[i][0])
    ans %= mod

print((nck(h-1 + w-1, h-1) - ans) % mod)

### FIXED CODE ###

h, w, n = map(int, input().split())
wall = [list(map(int, input().split())) for _ in range(n)]

wall.sort(key=lambda x: x[1])
wall.sort(key=lambda x: x[0])


# combination---

mod = 10**9 + 7
fac = [1, 1]
inv = [1, 1]
finv = [1, 1]
for i in range(2, h+w+1):
    fac.append(fac[i-1] * i % mod)
    inv.append(mod - inv[mod%i] * (mod//i) % mod)
    finv.append(finv[i-1] * inv[i] % mod)

def nck(n, k):
    if n < k:
        return 0
    if n < 0 or k < 0:
        return 0
    return fac[n] * (finv[k] * finv[n-k] % mod) % mod



# dp[i]:= i-1番目までの壁を通らず、i番目の壁にたどり着く経路の数
dp = [0] * n

for i in range(n):
    res = 0    # i-1までの壁を一回以上通って、i回目の壁にたどり着く経路数
    for j in range(i):
        # 最初にぶつかる壁がjで、iの壁に到達する経路数を求めていく
        res += dp[j] * nck(wall[i][0] - wall[j][0] + wall[i][1] - wall[j][1], wall[i][0] - wall[j][0])
        res %= mod
        
    # dp[i] = (i番目の壁までの経路数) - (i-1までの壁を一回以上通って、i回目の壁にたどり着く経路数)
    dp[i] = nck(wall[i][0] - 1 + wall[i][1] - 1, wall[i][0] - 1) - res
    dp[i] %= mod

# 余事象 ((h, w)までに少なくとも1つの壁にぶつかる経路数を数える)
ans = 0
for i in range(n):
    # 最初にぶつかる壁がiで、(h, w)に到達する経路数
    ans += dp[i] * nck(h - wall[i][0] + w - wall[i][1], h - wall[i][0])
    ans %= mod

print((nck(h-1 + w-1, h-1) - ans) % mod)