#include <iostream>
#include <vector>
using namespace std;
typedef long long ll;
const int maxn = 1000005;

int segment_tree[3 * maxn];

int merge_nodes(int A, int B) {
return A + B;
}
void build_tree(int L, int R, int node) {
if(L == R) {
segment_tree[node] = 0;
return;
}

int middle = (L + R) / 2;
build_tree(L, middle, 2 * node);
build_tree(middle + 1, R, 2 * node + 1);
segment_tree[node] = merge_nodes(segment_tree[2 * node], segment_tree[2 * node + 1]);
}

// L R i L R j L R
int query(int i, int j, int L, int R, int node) {
if(i <= L and R <= j) {
return segment_tree[node];
}
if(R < i or j < L) {
return 0;
}

int middle = (L + R) / 2;
return merge_nodes(query(i, j, L, middle, 2 * node), query(i, j, middle + 1, R, 2 * node + 1));

}
void update(int idx, int new_value, int L, int R, int node) {
if(L == R) {
segment_tree[node] = new_value;
return;
}
int middle = (L + R) / 2;

if(idx <= middle) {
update(idx, new_value, L, middle, 2 * node);
}
else {
update(idx, new_value, middle + 1, R, 2 * node + 1);
}

segment_tree[node] = merge_nodes(segment_tree[2 * node], segment_tree[2 * node + 1]);

}
int main() {
ios_base::sync_with_stdio(false);
int n;
cin >> n;

vector<int> v(n);
for(int i = 0; i < n; i++) {
cin >> v[i];
}

build_tree(0, n, 1);
ll res = 0;

for(int i = n - 1; i >= 0; i--) {
update(v[i], 1, 0, n, 1);
res += query(0, v[i] - 1, 0, n, 1);
}
cout << res << endl;

return 0;
}