#include
#include
#include
#include
using namespace std;
#define REP(i,n) for(int i=0;i<(n);++i)
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define RFOR(i,a,b) for(int i=(a);i>=(b);--i)
#define FOREACH(it,c) for(typeof((c).begin())it=(c).begin();it!=(c).end();++it)
#define CLR(x) memset((x),0,sizeof((x)))
typedef long long LL;
typedef vector VI;
typedef vector VS;
vector mm;
int n, m;
string s, t;
int dp(int i1, int i2) {
int& res = mm[i1][i2];
if (res != -1) return res;
if (i2 == m) return res = 1;
if (i1 == n) return res = 0;
res = 0;
FOR(i,i1,n-1) {
if (s[i] == t[i2]) res += dp(i + 1, i2 + 1);
}
return res;
}
class Solution {
public:
int numDistinct(string S, string T) {
n = S.length(), m = T.length();
s = S, t = T;
if (m > n) return 0;
if (m == n) return S == T ? 1 : 0;
mm.assign(n + 5, VI(m + 5, -1));
return dp(0, 0);
}
};
int main() {
Solution sol;
cout << sol.numDistinct("rabbbit", "rabbit") << endl;
return 0;
}