#include <iostream>
using namespace std;
int main()
{
int N, K[100], Sum=0, Temp=1;
cin >> N;
for (int i=0; i<N; i++)
cin >> K[i];
for(int i=0; i<N; i++)
{
if(K[i]==1)
{
Sum+=Temp;
Temp++;
}
else
Temp=1;
}
cout << Sum;
return 0;
}
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