#include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
template<class T>
using Table = vector<vector<T>>;
const ld eps=1e-9;

//// < "D:\D_Download\Visual Studio 2015\Projects\programing_contest_c++\Debug\a.txt"
int main() {
	while (1) {

		int L; cin >> L;
		if (!L)break;
		int ans = 22;
		for (int i = 0; i < 12; ++i) {
			int M, N; cin >> M >> N;
			L -= (M - N);
			if (L <= 0) {
				ans = min(ans,i + 1);
			}

		}
		if (ans != 22) {
			cout << ans << endl;
		}
		else {
			cout << "NA" << endl;
		}
	}
	return 0;
}