#include <bits/stdc++.h> using namespace std; const int N=6e5+1; #define ll long long string quary(string a,string b){ vector<int> u,v,d; u.resize(a.size()); v.resize(b.size()); d.resize(b.size()); int n=a.size(); for(int i=0;i<n;++i){ u[i]=a[i]-'a'; v[i]=b[i]-'a'; d[i]=(a[i]-b[i]+26)%26; } ll g=d[n-1]; for(int i=n-2;i>=1;--i){ g=(d[i]-g+26)%26; } if(g==d[0]){ return "da"; } return "ne"; } int main() { ios_base::sync_with_stdio(NULL); cin.tie(NULL); cout.tie(NULL); int n,q; cin>>n>>q; string a,b; cin>>a>>b; cout<<quary(a,b)<<'\n'; while(q--){ int p;char c; cin>>p>>c; a[p-1]=c; cout<<quary(a,b)<<'\n'; } return 0; }