Osajono

input/code.cpp: In function 'int main()':
input/code.cpp:12:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(int i = 0; i < s.length(); ++i) {
                             ^
input/code.cpp:15:23: error: invalid use of member function (did you forget the '()' ?)
 for (int i = 0; i < s.length; ++i) {
                       ^

#include <iostream>
#include <string>

using namespace std;

string s;
int cnt[30];
int res;

int main() {
cin>>s;
for(int i = 0; i < s.length(); ++i) {
cnt[s[i]-'A']++;
}
for (int i = 0; i < s.length; ++i) {
res += cnt[i] + cnt[i]*(cnt[i]-1)/2;
}
cout<<res<<"\n";
}