#include <bits/stdc++.h> using namespace std; int main(){ ios::sync_with_stdio(0);cin.tie(0); int n,q; cin >> n >> q; string a,b; cin >> a >> b; int cur = 0; for(int i = 0 ; i < n ; i++){ int A = a[i] - 'a'; int B = b[i] - 'a'; if(i % 2){ cur -= (A-B); } else{ cur += (A-B); } } if(cur % 26 == 0) cout << "da\n"; else cout << "ne\n"; while(q--){ int idx;char c; cin >> idx >> c; idx--; int old = a[idx] - 'a'; int ne = c - 'a'; a[idx] = c; if(idx % 2 == 0){ cur += (ne - old); } else{ cur -= (ne - old); } cout << (cur % 26 == 0 ? "da\n" : "ne\n"); } }