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#include "stdio.h"
int y,t,o;
int a(int x)
{
    if(x==1)
        return 0;
    if(x<=y)
        return (a(x-1)+y)%x;
    t=a(x-x/y);
    o=x%y;
    if(t<o)
        return t-o+x;
    else
        return t-o+(t-o)/(y-1);
    return 0;
}
int main()
{
    int b,c;
    scanf("%d",&b);
    while(b--)
    {
        scanf("%d %d",&c,&y);
        printf("%d\n",a(c));
    }
    return 0;
}
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