#include <bits/stdc++.h>

using namespace std;

#define maxn 85
char s[maxn];
int value = 0, score = 0;

int main() {
    scanf("%s", s);
    for (int m = 0; m < strlen(s); m++) {
        if (s[m] == 'O') score += 1;
        else score = 0;
        value += score;
    }
    printf("%d", value);
    return 0;
}