I am getting WA at Pretest 2 and the token which is differentiated is 252. I don't know if there is any corner cases, because it is passed at edge case like substring length = 7.Please help. The problem link is attached below 1605C - Dominant Character

My submission is stated below: 231633540

#include<bits/stdc++.h>
#define upper(s) transform(s.begin(),s.end(),s.begin(),::toupper)
#define lower(s) transform(s.begin(),s.end(),s.begin(),::tolower)
#define all(s) s.begin(),s.end()
#define rep(n) for(int i=0;i<n;i++)
#define repn(i,a,b) for(int i =a;i<b;i++)
#define showvec(v) for(int i=0;i<v.size();i++) cout<<v[i]<<" ";cout<<endl
#define showmap(m) for(auto i=m.begin();i!=m.end();++i) cout<<i->first<<" "<<i->second<<endl;
#define showset(s) for(auto i=s.begin();i!=s.end();++i) cout<<*i<<" ";cout<<endl;
#define ll long long
#define endl '\n'
#define int long long
#define pii pair<int,int>
using namespace std;

//x<<y is x*(2^y)
//x>>y is x/(2^y)



void solve()
{
    int n;
    cin>>n;
    string s;
    cin>>s;
    int mini = INT_MAX;
    vector<int> aIndex;
    vector<int> bOccur(n);
    vector<int> cOccur(n);
    bOccur[0] = s[0] == 'b' ? 1 : 0;
    cOccur[0] = s[0] == 'c' ? 1 : 0;
    for(int i = 0;i<n;i++)
    {
    	if(s[i] == 'a')
    		aIndex.push_back(i);
    }
    for(int i = 1;i<n;i++)
    {
    	bOccur[i] = (s[i] == 'b') ? bOccur[i-1]+1 : bOccur[i-1];
    	cOccur[i] = (s[i] == 'c') ? cOccur[i-1]+1 : cOccur[i-1];
    }
    if(aIndex.size() <= 1)
    {
    	cout<<"-1\n";
    	return;
    }
    int low = 0,high = 1;
    n = aIndex.size();
    while(low < high and high < n)
    {
    	if(bOccur[aIndex[high]] - bOccur[aIndex[low]] >= high - low + 1 or
    		cOccur[aIndex[high]] - cOccur[aIndex[low]] >= high - low + 1)
    	{
    		high++;
    	}
    	else
    	{
    		mini = min(mini,aIndex[high] - aIndex[low] + 1);
    		low = high;
    		high += 1;
    	}
    }
   	if(mini == INT_MAX)
   		cout<<"-1\n";
   	else
    	cout<<mini<<endl;
}


int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);cout.tie(nullptr);
    int t;
    cin>>t;
    while(t-->0)
    {
        solve();
    }
    return 0;
}