// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define int long long
#define endl "\n"
#define fi first
#define se second
const int M=26;
const int inf = 1e9;
const int LOG=17;
const int N=2e5+5;
int n , m , c , w , k , t=1 , q=1 , x , y , z , l , r;
void solve()
{   
    cin >> n >> q;
    string s,t;
    cin >> s >> t;
    string o=s;
    for (int i=0;i<n-1;i++){
        int u=(t[i]-o[i]+M)%M;
        o[i]=t[i];
        if (o[i+1]+u>'z'){
            o[i+1]=o[i+1]+u-M;
        }
        else{
            o[i+1]=o[i+1]+u;
        }
    }
    cout << (o[n-1]==t[n-1] ? "da" : "ne") << endl;
    for (int j=0;j<q;j++){
        char p;cin >> x >> p;
        s[--x]=p;
        string o=s;
        for (int i=0;i<n-1;i++){
            int u=(t[i]-o[i]+M)%M;
            o[i]=t[i];
            if (o[i+1]+u>'z'){
                o[i+1]=o[i+1]+u-M;
            }
            else{
                o[i+1]=o[i+1]+u;
            }
        }
        cout << (o[n-1]==t[n-1] ? "da" : "ne") << endl;
    }
}
signed main()    
{
    ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
    cin.tie(0), cout.tie(0);//DO NOT USE IN INTERACTIVE
    cout << fixed << setprecision(9);
    srand(time(0));
    // int t=1;
    // cin >> t;
    for (int _=1;_<=t;_++){
        solve();
        q++;
    }
} 
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