#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

void solve(int x){
    vector<int> M(12), N(12);
    int S = 0;
    for (int i = 0; i < 12; ++i) {
        cin >> M[i] >> N[i];
    }
    for (int i = 0; i < 12; ++i) {
        S += M[i]-N[i];
        if(S >= x){
            cout << i+1 << "\n";
            return;
        }
    }
    puts("NA");
}

int main() {
    int x;
    while(cin >> x, x){
        solve(x);
    }
    return 0;
}
