#include <iostream>
#include <cstdio>
using namespace std;
const int N = 1e5+10;
int q[N], tmp[N];
long long ms(int l, int r) {
if (l >= r) return 0; // 忘了写返回条件
long long ans = 0;
int mid = (l + r) >> 1;
ans += ms(l, mid) + ms(mid + 1, r); // l, mid mid+1, r
int i = l, j = mid + 1, k = 0; // i = l, j = mid + 1
while (i <= mid && j <= r) { // i <= mid, j <= r
if (q[i] <= q[j]) tmp[k++] = q[i++]; // 别写倒了
else {
tmp[k++] = q[j++];
ans += mid - i + 1;
}
}
while (i <= mid) tmp[k++] = q[i++]; // tmp =
while (j <= r) tmp[k++] = q[j++]; // tmp =
for (int i = l, j = 0; i <= r; ++i, ++j) q[i] = tmp[j];
return ans;
}
int main() {
int n;
scanf("%d", &n);
for (int i = 0; i < n; ++i) scanf("%d", &q[i]);
printf("%lld\n", ms(0, n - 1));
// for (int i = 0; i < n; ++i) printf("%d ", q[i]);
}