Preparing Olympiad

[code]#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int a[20];

int main(){
    int n,l,r,x;
    int sum;
    int ans = 0;

    scanf("%d%d%d%d",&n,&l,&r,&x);
    for(int i=0;i<n;i++) scanf("%d",&a[i]);
    for(int i=0;i<(1<<n);i++){
        sum=0;
        int mn=10000000;
        int mx=-1;
        int flag =0;
        for(int j=0;j<n;j++){
            if(i&(1<<j)){
                mn = min(a[j],mn);
                mx = max(mx,a[j]);
                sum+=a[j];
                }
        }
        if(sum>=l&&sum<=r&&mx-mn>=x)
        {
            ans++;
        }
    }
    printf("%d\n",ans);
}