#include<bits/stdc++.h>
using namespace std;
int main(){
	ios::sync_with_stdio(false);
    cin.tie(NULL);
	long long n,sum=0;cin>>n;
	while(n--){
		char ch;cin>>ch;
		int k=0;
		if(ch>='a'&&ch<='z'){
			k=ch-'a'+1;
			sum+=k;
		}else if(ch>='A' && ch<='Z'){
			k=ch-'A'-65;
			sum+=k;
		}
	}
	cout<<sum;

	return 0;
}