LCM, GCD

int lcm(int[] a){
    int lcm = 1;
    for (int v:a)
        lcm = lcm(lcm, v);
    return lcm;
}

int lcm(int a, int b){
    return a/gcd(a,b)*b;
}

int gcd(int a, int b){
    int c;
    while ( a != 0 ) {
        c = a;
        a = b%a;
        b = c;
    }
    return b;
}