#include 
#include 
using namespace std;
const int maxn = 3e5 + 10;

int main(){
    ios_base::sync_with_stdio(false);
    int n;
    cin >> n;
    vector > rank(n), type(n);
    for(int i = 0; i < n; i++) {
        cin >> rank[i].first;
        rank[i].second = i;
    }
    for(int i = 0; i < n; i++) {
        cin >> type[i].first;
        type[i].second = i;
        
    }
    
    vector > ans;
    while(true) {
        int min_difference = 2e9;
        int idx = -1;
        int i1 = -1, i2 = -1;
        for(int i = 0; i + 1 < rank.size(); i++) {
            if(type[i].first != type[i + 1].first) {
                if(abs(rank[i].first - rank[i + 1].first) < min_difference) {
                    min_difference = abs(rank[i].first - rank[i + 1].first);
                    idx = i;
                    i1 = rank[i].second + 1;
                    i2 = rank[i + 1].second + 1;
                }
            }
        }
        if(idx == -1) {
            break;
        }
        ans.push_back(make_pair(i1, i2));
        rank.erase(rank.begin() + idx);
        rank.erase(rank.begin() + idx);
        type.erase(type.begin() + idx);
        type.erase(type.begin() + idx);
    }
    cout << (int) ans.size() << "\n";
    for(int i = 0; i < ans.size(); i++) {
        cout << ans[i].first << " " << ans[i].second << "\n";
    }
       return 0;
}