#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
int diff (char a, char b){
	if (a > b){
		return ('z' - a + b - 'a' + 1);
	}
	else{
		return b - a;
	}
}
void solve(){
	int n, q; cin >> n >> q;
	string s, t; cin >> s >> t;
	
	s = "." + s, t = "." + t;
	int o = 0, e = 0;
	
	for (int i = 1; i <= n; i++){
		if (i % 2) o += diff(s[i], t[i]);
		else e += diff(s[i], t[i]);
	}
	
	if (e - o == 0) cout << "da" << endl;
	else cout << "ne" << endl;
	
	for (int Q = 1;  Q <= q; Q++){
		int idx; char C; cin >> idx >> C;
		if (idx % 2){
			o -= diff(s[idx], t[idx]);
			s[idx] = C;
			o += diff(s[idx], t[idx]);
		}
		else {
			e -= diff(s[idx], t[idx]);
			s[idx] = C;
			e += diff(s[idx], t[idx]);
		}
		if (e - o == 0) cout << "da" << endl;
		else cout << "ne" << endl;
	}
	
}
signed main(){
	ios::sync_with_stdio();
	cin.tie(0); cout.tie(0);
	
	int tc = 1;
	// cin >> tc;
	
	for (int i = 1; i <= tc; i++){
		solve();
	}
}
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