"""

A = 10だと
1からBまでの桁数

i桁目

"""

A = int(input())

B = input()
mod = 10**9+7

tenb = 0
for i in B:
    tenb *= A
    tenb += ord(i) - ord('0')
    tenb %= mod

ans = tenb * len(B)

#print (ans)

sml = 0
for i in range(len(B)):
    sub = pow(A,i,mod) - 1
    #print (i,sub)
    ans -= sub

print ((ans-tenb) % mod)

"""
tenb = 0
ans = 0
for i in B:
    tenb *= A
    tenb %= mod
    ans += tenb
    ans %= mod
    tenb += ord(i) - ord('0')
"""