/C06037 - Vòng tròn
<Problem>
https://code.ptit.edu.vn/student/question/C06037#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#define max(i, j) ((i > j) ? i : j)
int main() {
char s[200];
gets(s);
int res = 0;
for (int i = 0; i < strlen(s) - 1; i++) {
int p = 0;
for (int j = i + 1; j < strlen(s); j++) {
if (s[i] == s[j]) {
p = j;
}
}
if (p == 0 || p == i + 1) continue;
int cnt[200] = { 0 };
for (int j = i + 1; j < p; j++) {
cnt[s[j]]++;
}
for (int j = 'A'; j <= 'Z'; j++) {
if (cnt[j] == 1) res++;
}
}
printf("%d", res / 2);
printf("\n");
return 0;
}