#include<stdio.h>
#include<limits.h>

int INF = 999999999;

long long int merge(int S[], int left, int mid, int right){
	int i=0, j=0;
	long long int count=0;
	int n1 = mid-left;
	int n2 = right - mid;
	int L[n1], R[n2];
	
	for(i=0; i<n1; i++){
		L[i] = S[left + i];
	}
	for(i=0; i<n2; i++){
		R[i] = S[mid + i];
	}
	L[n1] = INF;
	R[n2] = INF;
	i=0; j=0;
	for(int k=left; k<right; k++){
		if(L[i]<=R[j]){
			S[k] = L[i];
			i++;
		}
		else{
			S[k] = R[j];
			j++;
			count += n1 - i;
		}
	}
	return count;
}

long long int mergeSort(int S[], int left, int right){
	int mid;
	long long int v1, v2, v3;
	mid = (left + right)/2;
	if( left+1<right ){
		mid = (left + right)/2;
		v1 = mergeSort(S, left, mid);
		v2 = mergeSort(S, mid, right);
		v3 = merge(S, left, mid, right);
		return v1 + v2 + v3;
	}
	else return 0;
}

int main(void){
	int n, i, S[500000];
	long long sum;
	scanf("%d", &n);
	for(i=0; i<n; i++){
		scanf("%d", &S[i]);
	}
	sum = mergeSort(S, 0, n);
	
	printf("%lld\n", sum);
	return 0;
}
