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include[HTML_REMOVED]
using namespace std;
typedef long long ll;
const int N = 100010;
ll n,num;
ll q[N],tem[N];
ll merge_sort(ll l,ll r){
if(l>=r)return 0;
ll mid = l+r>>1;
merge_sort(l, mid);
merge_sort(mid+1, r);
ll i=l,j=mid+1,k=0;
while(i<=mid&&j<=r){
if(q[i]<=q[j])tem[k++]=q[i++];
else {
num+=mid-i+1;
tem[k++]=q[j++];
}
}
while(i<=mid)tem[k++]=q[i++];
while(j<=r)tem[k++]=q[j++];
for(int i=l,k=0;i<=r;i++)q[i]=tem[k++];
return num;
}
int main(){
scanf(“%d”,&n);
for(int i=0;i<n;i++)scanf(“%d”,&q[i]);
cout<<merge_sort(0,n-1);
}
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