#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
template<class T> inline bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T&a,T b){if(a>b){a=b;return 1;}return 0;}
using ll = long long;

int n;

ll inversion_number(vector<int> &va, int n){
    if(n<=1) return 0;
    
    ll cnt=0;
    vector<int> vb(va.begin(),va.begin()+n/2), vc(va.begin()+n/2,va.end());
    cnt+=inversion_number(vb, vb.size())+inversion_number(vc, vc.size());

    int ai=0, bi=0, ci=0;
    while(ai<n){
        if(bi<vb.size() && (ci==vc.size() || vb[bi]<=vc[ci])) va[ai++]=vb[bi++];
        else cnt+=n/2-bi, va[ai++]=vc[ci++]; 
    }
    return cnt;
}

int main () {
    cin.tie(0); ios::sync_with_stdio(false); 

    cin >> n;
    vector<int> m(n);
    rep(i,n) cin >> m[i];
    cout << inversion_number(m,n) << endl;
}