#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
string dbmc = "\033[1;38;2;57;197;187m", dbrs = "\033[0m";
#define debug(x...) cout << dbmc << "[" << #x << "] : ", dout(x)
void dout() { cout << dbrs << endl; }
template <typename T, typename ...U>
void dout(T t, U ...u) { cout << t << (sizeof...(u) ? ", " : ""); dout(u...); }
#else
#define debug(...) 0
#endif
#define ll long long
#define pll pair<ll,ll>
#define pii pair<int,int>
#define fs first
#define sc second
#define tiii tuple<int,int,int>
#define tlll tuple<ll,ll,ll>
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int n,q;
cin>>n>>q;
string a,b;
cin>>a>>b;
int cnt[2] = {};
for(int i = 0;i<n;i++){
cnt[i&1] += (26+b[i]-a[i])%26;
}
cout<<(cnt[0]%26 == cnt[1]%26?"da\n":"ne\n");
while(q--){
int p;
char c;
cin>>p>>c;
p--;
cnt[p&1] -= (26+b[p]-a[p])%26;
a[p] = c;
cnt[p&1] += (26+b[p]-a[p])%26;
cout<<(cnt[0]%26 == cnt[1]%26?"da\n":"ne\n");
}
return 0;
}
