#include<bits/stdc++.h> using namespace std; typedef long long ll; typedef pair<int, int> pii; typedef pair<ll, ll> pll; #define pb push_back #define all(x) (x).begin(), (x).end() #define sz(x) (int) (x).size() #define endl '\n' int main() { cin.tie(0) -> sync_with_stdio(0); int n, q; cin >> n >> q; string a, b; cin >> a >> b; ll ans=0, ans1=0; for(int i = 0;i < n;i++) { if(i%2==0) ans+=a[i]-'a'; else ans-=a[i]-'a'; ans+=26; ans%=26; } for(int i = 0;i < n;i++) { if(i%2==0) ans1+=b[i]-'a'; else ans1-=b[i]-'a'; ans1+=26; ans1%=26; } cout << (ans==ans1?"da\n":"ne\n"); while(q--) { int i; char x; cin >> i >> x; i--; if(i%2==0) ans+=x-a[i]; else ans-=x-a[i]; a[i]=x; ans+=26; ans%=26; cout << (ans==ans1?"da\n":"ne\n"); } }