codeforces 1324E（dp）

#include<bits/stdc++.h>
#define x first
#define y second
#define PB push_back
#define mst(x,a) memset(x,a,sizeof(x))
#define all(a) begin(a),end(a)
#define rep(x,l,u) for(ll x=l;x<u;x++)
#define rrep(x,l,u) for(ll x=l;x>=u;x--)
#define sz(x) x.size()
#define IOS ios::sync_with_stdio(false);cin.tie(0);
using namespace std;
typedef unsigned long long ull;
typedef pair<int,int> PII;
typedef pair<long,long> PLL;
typedef pair<char,char> PCC;
typedef long long ll;
const int N=2020;
const int M=1e6+10;
const int INF=0x3f3f3f3f;
const int MOD=1e9+7;
int a[N],f[N][N];
int n,h,l,r;
int check(int x){
    if(x>=l && x<=r) return 1;
    return 0;
}
void solve(){
    cin>>n>>h>>l>>r;
    rep(i,1,n+1) cin>>a[i];
    mst(f,-1);
    f[0][0]=0;
    rep(i,1,n+1){
        rep(j,0,h){
            if(f[i-1][j]!=-1){
                int t=(a[i]+j)%h;
                f[i][t]=max(f[i][t],f[i-1][j]+check(t));
                t=(a[i]+j-1+h)%h;
                f[i][t]=max(f[i][t],f[i-1][j]+check(t));
            }
        }
    }
    int ans=0;
    rep(i,0,h) ans=max(ans,f[n][i]);
    cout<<ans<<endl;
}
int main(){
    IOS;
    //int t;cin>>t;
    //while(t--)
        solve();
    return 0;
}