Not getting desired output. Is there something inherently wrong in the logic?

the input depicts no of tests followed by size of input array followed by the array and the output either gives -1 or the square of the largest prime in the given array. I am providing the code and the expected and actual output along with sample standard input used.

standard input:
3
5
1 4 6 8 10
3
2 2 9
2
156 13

expected output | getting
-1                -1
4                  4
169               -1


#include <stdio.h>
int main(){
int test,size;
int i,j;
scanf("%dn",&test);
while(test>=1){
    scanf("%dn",&size);
    int data[size],factors=0,max=0;
    for(i=0;i<size;i++){
        scanf("%d ",&data[i]);
        for(j=1;j<=data[i];j++){
            if(data[i]%j==0){
                factors+=1;
            }
        }
        if((factors==2) && (data[i]>max)){
            max=data[i];
        }
    }
    if(max>=2){
        printf("%dn",max*max);
    }else{
        printf("%dn",-1);
    }
    max=0;
    test-=1;
    }
}