新手求助，莫名累加器无法工作

#include <bits/stdc++.h>
using namespace std;
int main()
{
    int a[10],n;
    int s=10;
    for (int i;i<=10;++i)
        cin >>a[i];
    cin >> n;
    n+=30;
    for (int i;i<=10;++i)
        if (a[i]>=n)
            s-=1;
    cout << s;
    return 0;
}