mod = 10 ** 9 + 7
a = int(input())
b = int(input())
stb = str(b)
n = len(stb)

b10 = 0
for i in range(n):
    b10 *= a
    b10 += int(stb[i])

ans = 0
for i in range(n - 1):
    ans += i * pow(a, i, mod) * (a - 1)
    ans %= mod
ans = (ans + (n - 1) * (b10 - pow(a, n - 1, mod) + 1)) % mod
print(ans)