#include<iostream>
using namespace std;
int main() {
	int a, ans,moku, b, tyokin;
	while (1) {
		cin >> moku;
		tyokin = 0;
		ans = 0;
		for (int i = 1; i <= 12; i++) {
			cin >> a >> b;
			tyokin += a - b;
			if (moku <= tyokin) {
				ans = i;
				tyokin = -99999999;
			}
		}
		if (ans == 0) {
			cout << "NA" << endl;
		}
		else {
			cout << ans << endl;
		}
	}
}
