function isPrime1(n) {
if (isNaN(n) || !isFinite(n) || n%1 || n<2) return false;
var m=Math.sqrt(n);
for (var i=2;i<=m;i++) if (n%i==0) return false;
return true;
}
function isPrime2(n) {
if (isNaN(n) || !isFinite(n) || n%1 || n<2) return false;
if (n%2==0) return (n==2);
var m=Math.sqrt(n);
for (var i=3;i<=m;i+=2) {
if (n%i==0) return false;
}
return true;
}
function isPrime3(n) {
if (isNaN(n) || !isFinite(n) || n%1 || n<2) return false;
if (n%2==0) return (n==2);
if (n%3==0) return (n==3);
var m=Math.sqrt(n);
for (var i=5;i<=m;i+=6) {
if (n%i==0) return false;
if (n%(i+2)==0) return false;
}
return true;
}
function isPrime4(n) {
if (isNaN(n) || !isFinite(n) || n%1 || n<2) return false;
if (n==leastFactor(n)) return true;
return false;
}
leastFactor = function(n){
if (isNaN(n) || !isFinite(n)) return NaN;
if (n==0) return 0;
if (n%1 || n*n<2) return 1;
if (n%2==0) return 2;
if (n%3==0) return 3;
if (n%5==0) return 5;
var m = Math.sqrt(n);
for (var i=7;i<=m;i+=30) {
if (n%i==0) return i;
if (n%(i+4)==0) return i+4;
if (n%(i+6)==0) return i+6;
if (n%(i+10)==0) return i+10;
if (n%(i+12)==0) return i+12;
if (n%(i+16)==0) return i+16;
if (n%(i+22)==0) return i+22;
if (n%(i+24)==0) return i+24;
}
return n;
}
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