#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>

#define INFTY 999999999
unsigned long long  count;

void merge(int *A,int left,int mid,int right){
	int n1=(mid-left);
	int n2=(right-mid);
	int *L,*R;
	L=(int*)malloc(sizeof(int)*(n1+1));
	R=(int*)malloc(sizeof(int)*(n2+1));
	for(int i=0;i<n1;i++){
		L[i]=A[left+i];
	}
	for(int i=0;i<n2;i++){
		R[i]=A[mid+i];
	}

	L[n1]=INFTY;
	R[n2]=INFTY;
	int i=0,j=0;
	for(int k=left;k<(right);k++){
		if(L[i]<=R[j]){
			A[k]=L[i];
			i++;

		}else{
			A[k]=R[j];
			j++;
			count+=(n1-i);
		}
		
	}
	free(L);
	free(R);
}

void mergeSort(int *A,int left,int right){
	int mid;
	if((left+1)<right){
		mid=((left+right)/2);
		mergeSort(A,left,mid);
		mergeSort(A,mid,right);
		merge(A,left,mid,right);
	}
}

void calc(int *A,int N){	
	count=0;
	mergeSort(A,0,N);
	printf("%llu\n",count);
}

int main(){
	int N;
	int *A;
	
	scanf("%d",&N);
	A=(int*)malloc(sizeof(int)*N);
	for(int i=0;i<N;i++){
		scanf("%d",&A[i]);
	}

	calc(A,N);
	//printf("%d\n",calc(A,N));

	return 0;
}
