#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/

int N,K;
int DP[300][90000];
int MOD = 1e9 + 7;

void solve() {
    cin>>N>>K;
    REP(i,N)cin.ignore();
    
    REP(i,N)REP(j,K+1)DP[i][j]=0;
    DP[0][0]=1;
    FOR(i,1,N) {
        int sum = 0;
        REP(j,K+1) {
            DP[i][j] = DP[i-1][j] + sum;
            DP[i][j] %= MOD;
            sum += DP[i-1][j];
            if (j>=i) {
                sum += MOD - DP[i-1][j-i];
            }
            sum %= MOD;
        }
    }
    int ans = 0;
    REP(j,K+1) {
        ans += DP[N-1][j];
        ans %= MOD;
    }
    
    cout << ans << endl;
}