#include<bits/stdc++.h>
using namespace std;
int maxn;
struct cnmlgb{
int leader;
char support;
}people[1000010];
int n;
int sum[1000010];
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		people[i].leader=i;
		cin>>people[i].support;
		people[i].support=people[i].support-'A'+10;
	}
	for(int i=1;i<=n;i++){
		if(people[i].support>maxn){
			maxn=people[i].support;
		}
	}
	for(int i=1;i<=n;i++){
		if(people[i].support==maxn){
			cout<<people[i].leader<<people[i].support;
		}
	}
	return 0;
}