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#include<cstdio>
#include<cmath>
#include<iostream>

#define ug using
#define nespe namespace
#define sd std
#define it int
#define mn main
#define ll long long
#define sf scanf
#define pw pow
#define i if
#define q 1e9
#define pf printf
#define ee else
#define rn return
#define k 0
#define ww ==
#define w =
#define nw <=
ug nespe sd;
it mn(){
    it a, b;
    ll f;
    sf("%d %d",&a,&b);
    f w pw(a,b);
    i(f nw (it)q && f ww pw(a,b)){
        pf("%lld",f);
    }ee{
        pf("-1");
    }
    rn k ;
}