#include <stdio.h>
#include <stdlib.h>
#define iMAX 1000000000

long long marge ( long *A, long left, long mid, long right)
{
    long d1,d2,i,j,k;
    long long cnt=0l;
    d1 = mid - left;
    d2 = right - mid;
    long *L = malloc(sizeof(long long)*(d1+1));
    long *R = malloc(sizeof(long long)*(d2+1));
    
    for( i=0l; i<d1; i++ ) L[i] = A[left+i];
    for( i=0l; i<d2; i++ ) R[i] = A[mid+i];

    L[d1] = iMAX;
    R[d2] = iMAX;

    for( k=left,i=0l,j=0l; k<right; k++ )
    {
        if( L[i] <= R[j] )
        {
            A[k] = L[i++];
        }else{
            A[k] = R[j++];
            cnt += d1-i;
        }
    }
    
    free(L);
    free(R);
    return cnt;
}


long long margeSort( long  *A, long  left,  long right)
{
    long mid;
    long long cnt=0l;
    
    if( left+1l < right )
    {
        mid = ( left + right ) /2l;
        cnt += margeSort( A, left, mid );
        cnt += margeSort( A, mid, right );
        cnt += marge( A, left, mid, right );
    }
    
    return cnt;
}


int main()
{
    long n,i;
    scanf( "%ld", &n );
    long *S = malloc(sizeof(long)*n);
    
    for( i=0l; i<n; i++ ){
        scanf( "%ld", &S[i] );
    }
    
    printf( "%lld\n",margeSort( S, 0l, n ));
    free(S);
    return 0;
}
