/*
██████╗ █████╗ ███████╗██╗ ██╗██╗██████╗
██╔══██╗██╔══██╗██╔════╝██║ ██║██║██╔══██╗
██████╔╝███████║███████╗███████║██║██║ ██║
██╔══██╗██╔══██║╚════██║██╔══██║██║██║ ██║
██║ ██║██║ ██║███████║██║ ██║██║██████╔╝
╚═╝ ╚═╝╚═╝ ╚═╝╚══════╝╚═╝ ╚═╝╚═╝╚═════╝
*/
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ll long long
#define ull unsigned long long
#define ld long double
#define str string
#define ch char
#define db double
#define pb push_back
#define ff first
#define ss second
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define YES cout<<"YES\n";
#define NO cout<<"NO\n";
#define Bob cout<<"Bob\n";
#define Alice cout<<"Alice\n";
#define ordered_set tree<pair<ll, ll>, null_type,less<pair<ll,ll>>,rb_tree_tag,tree_order_statistics_node_update>
const ll MOD=1e9+7;
const ll INF = 10000000000;
void solve(){
ll n,d;
cin>>n>>d;
vector<ll>a(n+1);
for(ll i = 1;i<=n;i++)cin>>a[i];
ll cnt=0;
ll idx = 0;
for(ll i = 2;i<=n;i++){
if(a[i]==1){
cnt++;
idx=i;
}
}
ll ans = cnt;
for(int i = 3;i<=idx;i++){
if(a[i]==0){
ans+=cnt;
}
else{
ans+=cnt;
cnt--;
}
}
cout<<ans;
}
signed main(){
ll t=1;
//cin>>t;
while(t--){
solve();
}
return 0;
}
