#include <bits/stdc++.h> using namespace std;

int main() { int a[100005]; int n, b; cin >> n >> b; for (int i = 1; i <= n; i++) { cin >> a[i];

}
for (int j = 1; j <= n; j++) {
	b = b - a[j];
	if (b <= 0) {
		cout << j;
		break;
	}
}
if (b > 0) {
	cout << "-1";
}

return 0;

}