#include <string>
#include <vector>
using namespace std;
int solution(int n)
{
int answer = 0;
int i, j;
for(i = 2; i <= n; i++)
{
for(j = 2; j * j <= i; j++)
{
if(i % j == 0)
{
answer++;
break;
}
else
{
;
}
}
}
answer = n - answer - 1;
return answer;
}