What is the error in my "Fibonacci String" solution?

This is my solution for Fibonacci String : Solution

First I sort the given string, then push the occurance of all uniqe characters in a vector. Then I search for the triplet where
v(i) = v(j) + v(k)

But when I submit the solution I keep getting WA. Can someone please help me find my mistake.

“If any such permutation of the elements of C satisfies f(c_i)=f(c_i−1)+f(c_i−2) for all i≥3, the string is said to be a dynamic string.”

It says for all i , not for any i

while (j < k) {
			if (arr[i] == arr[j] + arr[k]) {
				cout << "Dynamic" << endl;

Looks like you’re checking for any i.

Ok thank you…so what should do to check for all ’ i ’ ?