This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
#define LCBorz ios_base::sync_with_stdio(false); cin.tie(0);
#define int long long
#define all(x) x.begin(), x.end()
#define endl '\n'
const int N=200005;
const int INF=1e18;
const int C=26;
int32_t main() {
    LCBorz;
    int n,q;cin>>n>>q;
    string s,t;cin>>s>>t;
    int a=0,b=0;
    for(int i=0;i<n;i++){
        if(i&1)a=(a+s[i]-'a')%C;
        else a=(a-s[i]+'a'+C)%C;
    }
    for(int i=0;i<n;i++){
        if(i&1)b=(b+t[i]-'a')%C;
        else b=(b-t[i]+'a'+C)%C;
    }
    cout<<(a==b?"da":"ne")<<endl;
    for(int i=0;i<q;i++){
        int p;char c;cin>>p>>c;
        p--;
        if(p&1)a=(a+c-s[p]+C)%C;
        else a=(a-c+s[p]+C)%C;
        s[p]=c;
        cout<<(a==b?"da":"ne")<<endl;
    }
    return 0;
}
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