int main()
{
cout << "Hello world!" << endl;
int m,n,r;
cout << "m=";
cin >> m;
cout << "n=";
cin >> n;
for (int i=0; i<100; i++)
{
r = m%n;
cout << "m=" << m << "\\tn=" << n << "\\tr=" << r << endl;
if (0==r) break;
m = n;
n = r;
}
cout << "n=" << n;
return 0;
}