``#include #include using namespace std;

int main() { int k; string s; cin >> k >> s;

int n = s.length();
int count = 1; // 当前字符连续出现的次数

for (int i = 1; i <= n; i++) {
    if (i < n && s[i] == s[i-1]) {
        count++;
    } else {
        // 当前连续段结束
        if (count >= k) {
            cout << s[i-1] << endl;
            return 0;
        }
        count = 1;
    }
}

cout << "No" << endl;

return 0;

}******

#include<bits/stdc++.h>
using namespace std;
int main(){
	char a[1001];
	int n,cnt=1;
	cin>>n>>a;
	for(int i=1;i<=strlen(a);i++){
		cin>>a[i];
		if(a[i]==a[i-1])
			cnt++;
		else
			cnt=1;
		if(cnt==n){
			cout<<a[i];
			return 0;
		}
	}
	cout<<"No";
	return 0;
}