#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pll> pip;
const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-9;

int l;
int m[12], n[12];

int main() {
	while (cin >> l, l) {
		REP(i, 12) scanf("%d %d", m + i, n + i);
		
		int ans = -1, sum = 0;
		REP(i, 12) {
			sum += m[i] - n[i];
			if (sum >= l) { ans = i + 1; break; }
		}
		
		if (ans == -1) puts("NA");
		else cout << ans << endl;
		
	}
	return 0;
}