class Solution:

# @return an integer

def numDistinct(self, S, T):

m = len(S)

n = len(T)

dp = [[0 for j in range(m + 1)] for i in range(n + 1)]

for j in range(m + 1):

dp[0][j] = 1

for i in range(1, n + 1):

for j in range(1, m + 1):

dp[i][j] = dp[i][j - 1]

if T[i - 1] == S[j - 1]:

dp[i][j] += dp[i - 1][j - 1]

return dp[n][m]