The Bus Driver Problem

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn = 100+5;
int day[maxn], night[maxn], n, d, r;
int cmp(int a, int b) {
return a>b;
}
int main() {
while(scanf("%d%d%d", &n, &d, &r) != EOF && (n+d+r)) {
for(int i=0; i<n; i++) {
scanf("%d", &day[i]);
}
for(int i=0; i<n; i++) scanf("%d", &night[i]);
sort(day, day+n);
sort(night, night+n, cmp);
int sum = 0;
for(int i=0; i<n; i++) {
int ans = day[i]+night[i];
if(ans>d)
sum += r*(ans-d);
}
printf("%d\n", sum);

}
return 0;
}