mod = int(1e9 + 7)
a = int(input())
b = int(input())
x = 0
for v in str(b):
    x *= a
    x += int(v)
    x %= mod
i = a
res = 0
for _ in range(len(str(b)) - 1):
    res += x - i + 1
    res %= mod
    i *= a
    i %= mod
print(res)