#include<iostream>
#include <stdlib.h>
#include<string>
#include<algorithm>
using namespace std;
int main()
{
int n;
int x[100];
cin >> n;
int j = 0;
int i = 0;
int count = 0;
int count1 = 0;
int count2 = 0;
int a;
int c = 0;
for (int k = 0; k < n; k++)
{
cin >> x[k];
if (x[k + 1] == 0)
{
i = k + 1;
//cout << i << endl;
break;
}
}
for (int k = 0; k < n; k++)
{
if (x[n-1] == 0)
{
j = n;
//cout << j << endl;
break;
}
else
{
n = n - 1;
if (x[n-1] == 0)
{
j = n;
// cout << j << endl;
break;
}
}
}
for (int m=i; i< j; i++)
{
if (x[0] == 1)
{
count1 = x[0];
}
if (x[n] == 1)
{
count2++;
}
a = 1 - x[i];
//cout << a << endl;
if (a == 1)
{
count++;
}
}
c = count1 + count2 + count;
cout << c << endl;
}
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