Что в коде не так?

#include
#include
#include
using namespace std;
int main() {
string s;
vector vowels = ('a','e','i','o','u','y');
cin >> s;
int count_letters = 0;
int count = 0;
int state = -1;
int c = state;
for(int i = 0 ;i < s.length(); i++, c = state) {
if(find(vowels.begin(),vowels.end(),s[i])!= vowels.end())
state = 0;
else state = 1;
if(c==state) count_letters++;
if(count_letters == 3) {
count_letters = 1;
count++;
}
}
cout << count ;
}


In function 'int main()':
conversion from char to non-scalar type requested
cin was not declared in this scope
cout was not declared in this scope