as im submitting the code below its showing a wrong answer

/*created by raghavyadavm*/

include<stdio.h>

int main() { int n,i,j,flag=0; unsigned int a[100001],b[100001];

do
{
    scanf("%d",&n);
    flag=0;

    if(n)
    {
        for(i=1;i<=n;i++)            //reading and storing
        {
            scanf("%d",&a[i]);
            b[a[i]]=i;

        }

        for(i=1;i<=n;i++)
        {
            if(a[i]==b[i])
                flag++;      //comparing

        }

        if(flag==n)
            printf("ambiguous\n");
        else
            printf("unambiguous\n");

    }

}while(n);


return 0;

}