#include<iostream>
using namespace std;
int ucln( int a, int b)
{
while(a!=b)
{
if(a>b)a=a-b;
else b=b-a;
}
return a;
}
int main()
{
int a, b, c, d;
cout<<"a=";cin>>a;
cout<<"b=";cin>>b;
cout<<"c=";cin>>c;
cout<<"d=";cin>>d;
int d1;
d1=ucln(a,b);
int d2;
d2=ucln(c,d);
int u;
u=ucln(d1,d2);
cout<<"uoc chung lon nhat cua 4 so la: "<<u<<endl;
system("pause");
}

#include<iostream>
using namespace std;
int main()
{
int a, b, c, d;
cout<<"a=";cin>>a;
cout<<"b=";cin>>b;
cout<<"c=";cin>>c;
cout<<"d=";cin>>d;
int u;
u=a*b*c*d;
int max;
max=a;
if(b>max) max=b;
if(c>max) max=c;
if(d>max) max=d;
int f;
for(int i=u;i>=max;i--)
{
if((i%a==0)&&(i%b==0)&&(i%c==0)&&(i%d==0))f=i;
}
cout<<"boi chung nho nhat cua 4 so la: "<<f<<endl;
system("pause");
}