a=input()
t=0
for i in range(len(a)):
if a[i]=='i' or a[i]=='I':
if a[i+1]=='I':
t=i+1
break
else:
t=-1
else:
t=-1
if t<=0:
print('-1')
else:
print(t+1)
YT1pbnB1dCgpCnQ9MApmb3IgaSBpbiByYW5nZShsZW4oYSkpOgoJaWYgYVtpXT09J2knIG9yIGFbaV09PSdJJzoKCQlpZiBhW2krMV09PSdJJzoKCQkJdD1pKzEKCQkJYnJlYWsKCQllbHNlOgoJCQl0PS0xCgllbHNlOgoJCXQ9LTEKaWYgdDw9MDoKCXByaW50KCctMScpCmVsc2U6CglwcmludCh0KzEp