#include <stdio.h>
#include <string.h>

typedef long long ll;
ll left[100005];//从左边开始到第i个有多少个T
ll right[100005];//从右边开始到第i个有多少个T
char s[100005];
int main() {
	while (scanf("%s", s+1) != EOF) {
        int len = strlen(s+1);
        for (int i = 1; i <= len; i++) {
            if (s[i] == 'T') left[i] = left[i - 1] + 1;
            else left[i] = left[i - 1];
        }
        for (int i = len; i >= 1; i--) {
            if (s[i] == 'T') right[i] = right[i + 1] + 1;
            else right[i] = right[i + 1];
        }
        ll sum = 0;
        for (int i = 1; i <= len; i++) {//枚举每一个A
            if (s[i] == 'A') sum += (left[i] * right[i]);
        }
        printf("%lld\n", sum);
	}
    return 0;
}