1 #include <bits/stdc++.h>
2 using namespace std;
3 const int MAXN=1e5+10;
4 int a[MAXN];
5 int temp[MAXN];
6 long long ans;
7 void merge(int l,int mid,int r)
8 {
9 int i=l;
10 int j=mid+1;
11 int k=l;
12 while(i<=mid&&j<=r)
13 {
14 if(a[i]<=a[j])
15 {
16 temp[k++]=a[i++];
17 }
18 else
19 {
20 ans+=j-k;//记录数量;
21 temp[k++]=a[j++];
22 }
23 }
24 while(i<=mid)
25 temp[k++]=a[i++];
26 while(j<=r)
27 temp[k++]=a[j++];
28 for (int s = l; s <=r; ++s) {
29 a[s]=temp[s];
30 }
31
32 }
33
34 void mergesort(int l,int r)
35 {
36 if(l<r)
37 {
38 int mid=(l+r)/2;
39 mergesort(l,mid);
40 mergesort(mid+1,r);
41 merge(l,mid,r);
42 }
43 }
44 int main()
45 {
46 int n,x,y;
47 while(scanf("%d%d%d",&n,&x,&y)!=EOF) {
48 ans=0;
49 memset(temp,0,sizeof(temp));
50 for (int i = 0; i <n ; ++i) {
51 scanf("%d",&a[i]);
52 }
53 mergesort(0,n-1);
54 printf("%lld\n",ans);
55 }
56 return 0;
57 }
