include <iostream>

include <cstdio>

using namespace std; int n,ans,a[50000],b[50000]; void gsort(int s,int t) { if(s==t) return; int i,j,k=s,mid=(s+t)/2; gsort(s,mid); gsort(mid+1,t); i=s,j=mid+1; while(i<=mid&&j<=t) { if(a[i]<=a[j]) b[k++]=a[i++]; else { b[k++]=a[j++]; ans+=mid-i+1; } } while(i<=mid) b[k++]=a[i++]; while(j<=t) b[k++]=a[j++]; for(i=s;i<=t;i++) a[i]=b[i];

}
int main(int argc, char *argv[])
{
scanf("%d",&n);
for(int i=1;i<=n;i++) scanf("%d",&a[i]);
gsort(1,n);
printf("%d\n",ans);
return 0;

}