#include<iostream> using namespace std; int N; int A[2<<17]; main() { cin>>N; for(int i=0;i<N;i++)cin>>A[i]; long ans=(long)N*(N+1)/2; for(int i=0;i<N;) { if(A[i]==0) { i++; continue; } int r=i; while(r<N&&A[r]==1)r++; int len=r-i; i=r; ans-=(long)len*(len+1)/2; } cout<<ans<<endl; }