Help me in solving EZSPEAK problem

help
,
1

My issue

My hidden test case is failing, but the sample test case is passed.
What I did was, I kept a counter, which increments, when the scanned char is vowel. After that, I have kept an only if, which prints no if the count is >4
All this inside an for loop.

Please help

My code

#include <stdio.h>
#include<string.h>

int is_vowel(char c)
{
    return c=='a' || c=='e' || c=='i' || c=='o' || c=='u' ;
}


int main() 
{
    int n;
    int t;
    char s[100];
    scanf("%d",&n);
    while(n--)
    {
        scanf("%d",&t);
        scanf("%s",s);
        int count=0;
        for(int i=0;i<=t;i++)
        {
            if(strchr("aeiou",s[i])==NULL)
            {
                count++;
            }
             else
            {
                count+=0;
            }
            
            if(count>4)
                {
                    printf("NO\n");
                    break;
                }
        }
        
        
        if(count<=4)
        {
            printf("YES\n");
        }
    }
    return 0;
}

Learning course: Roadmap to 3*
Problem Link: https://www.codechef.com/learn/course/klu-roadmap-3star/KLURMP300A/problems/EZSPEAK