#include <string>
#include <vector>
using namespace std;
string solution(vector<int> food)
{
string answer = "";
int i, j, size = food.size();
int m;
for(i = 1; i < size; i++)
{
m = food[i] / 2;
for(j = 0; j < m; j++)
{
answer += (i + 48);
}
}
size = answer.length();
answer += '0';
for(i = size - 1; i >= 0; i--)
{
answer += answer[i];
}
return answer;
}