#include<iostream>
#include<string>
using namespace std;
string S;
int main() {
cin >> S;
int cnt = 0;
for (int i = 0; i < S.size(); i++) {
if (S[i] == 'I' && cnt % 2 == 0) {
cnt++;
}
else if (S[i] == 'O' && cnt % 2 == 1) {
cnt++;
}
}
if (cnt % 2 == 0 && cnt >= 1) { cnt--; }
cout << cnt << endl;
return 0;
}
I2luY2x1ZGU8aW9zdHJlYW0+CiNpbmNsdWRlPHN0cmluZz4KdXNpbmcgbmFtZXNwYWNlIHN0ZDsKc3RyaW5nIFM7CmludCBtYWluKCkgewoJY2luID4+IFM7CglpbnQgY250ID0gMDsKCWZvciAoaW50IGkgPSAwOyBpIDwgUy5zaXplKCk7IGkrKykgewoJCWlmIChTW2ldID09ICdJJyAmJiBjbnQgJSAyID09IDApIHsKCQkJY250Kys7CgkJfQoJCWVsc2UgaWYgKFNbaV0gPT0gJ08nICYmIGNudCAlIDIgPT0gMSkgewoJCQljbnQrKzsKCQl9Cgl9CglpZiAoY250ICUgMiA9PSAwICYmIGNudCA+PSAxKSB7IGNudC0tOyB9Cgljb3V0IDw8IGNudCA8PCBlbmRsOwoJcmV0dXJuIDA7Cn0=