/*
VIM: let g:lcppflags="-std=c++11 -O2 -pthread"
VIM: let g:wcppflags="/O2 /EHsc /DWIN32"
VIM: let g:argv=""
*/
#include <iostream>
#include <stdexcept>
#include <vector>
#include <algorithm>
#include <string>

/*
int solution(vector<int>& A) {
	int n = A.size();
	int i = n - 1;
	int result = -1;
	int k = 0;
	int maximal = 0;
	while (i > 0) {
		if (A[i] == 1) {
			k = k + 1;
			if (k >= maximal) {
				maximal = k;
				result = i;
			}
		}
		else {
			k = 0;
		}
		i = i - 1;
	}
	if (A[i] == 1 && k + 1 > maximal)
		result = 0;
	return result;
}
*/

using namespace std;

int solution(vector<int>& A) {
	int n = A.size();
	int i = n - 1;
	int result = -1;
	int k = 0;
	int maximal = 0;
	while (i > 0) {
		if (A[i] == 1) {
			k = k + 1;
			if (k >= maximal) {
				maximal = k;
				result = i;
			}
		}
		else {
			k = 0;
		}
		i = i - 1;
	}
	if (A[i] == 1 && k + 1 >= maximal)
		result = 0;
	return result;
}

int main ( void )
{try{
#if 1
	std::vector<int> a = {
		1,1,1,0,1,1,1,0,1
	};

	std::cout << solution( a ) << std::endl;
	
#endif
	return 0;
}
catch ( const std::exception& e )
{
	std::cerr << std::endl
			<< "std::exception(\"" << e.what() << "\")." << std::endl;
	return 2;
}
catch ( ... )
{
	std::cerr  << std::endl
			<< "unknown exception." << std::endl;
	return 1;
}}