Codeforces Round #432 (Div. 1) B. Arpa and a list of numbers

#include<iostream>
#include<map>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<set>
#include<vector>
#include<queue>
#include<stack>
#include<algorithm>
using namespace std;
typedef long long ll;
const int N = 1e6+5;
#define MS(x,y) memset(x,y,sizeof(x))
#define MP(x, y) make_pair(x, y)
const int INF = 0x3f3f3f3f;

ll sum
;
int cnt
;
int isprime
;

int j;
ll Sum(int x) {
if(x <= j) return sum[j];
else if(x >= N) return sum[N-1];
else return sum[x];
}
int Cnt(int x) {
if(x <= j) return cnt[j];
else if(x >= N) return cnt[N-1];
else return cnt[x];
}
int main() {
int n, x, y;
while(~scanf("%d %d %d", &n, &x, &y)) {
int ed = x/y;
for(int i = 0; i < n; ++i) {
int a; scanf("%d", &a);
sum[a] += a;
cnt[a] ++;
}
for(int i = 1; i < N; ++i) {
sum[i] += sum[i-1];
cnt[i] += cnt[i-1];
}
ll ans = 1e18;

for(int i = 2; i < N; ++i) {
if(!isprime[i]) {
ll tmp = 0;
for(j = 0; j < N; j += i) {
isprime[j] = 1;

int fr1 = j + i - 1; int to1 = j + i - ed - 1;   int fr2 = j + i - ed - 1; int to2 = j;

ll t1 = Sum(fr1) - Sum(to1); int t2 = Cnt(fr1) - Cnt(to1);
int t3 = Cnt(fr2) - Cnt(to2);
//  if(i == 17 && j < 20) printf("%d %lld %d %d %lld\n", j, t1, t2, t3, tmp);

tmp += 1ll*(1ll*t2*(j+i) - t1) * y + 1ll* t3 * x;
}
ans = min(ans, tmp);
}
}
printf("%lld\n", ans);
}
return 0;
}