Wobbly Numbers

/*
An $N$-length wobbly number is of the form "ababababab..." and so on of length $N$, where $a!=b$.

Find $K$^$th$ wobbly number from a lexicographically sorted list of $N$-length wobbly numbers. If the number does not exist print $-1$ else print the $K$^$t$h wobbly number.

Input:
First line contains $T$ - number of test cases
Each of the next $T$ lines contains two space separated integers - $N$ and $K$

Output:
For each test case print the required output in a new line. 

Constraints: $1\le T\le 100$
$3\le N\le 1000$
$1\le K\le 100$
*/ 

#include <stdio.h>

int main()
{
    int t,i,n,k,a,b,j,temp;

    scanf("%d",&t);
    for(i=0;i<t;i++){
        scanf("%d %d",&n,&k);
       
        if(k>81)
            printf("-1\n");
        else{
            a=ceil((double)k/9.0);
            temp=k-9*(a-1);
            b=(temp<=a)?temp-1:temp;
            for(j=0;j<n;j++)
                if(j%2==0) printf("%d",a);
                else printf("%d",b);
            printf("\n");
        }
    }

}