程序代码：

# include "stdio.h"

int main(void)

{
    void hcf(int, int);
    
    int u, v;
    
    scanf("%d %d", &u, &v);
    
    hcf(u, v);
    
    return 0;
}

void hcf (int u, int v)

{
    int t, r;
    
    if (v > u)
    {
        t = u; u = v; v = t;
    }
    
    while ((r = u%v) != 0)
    {
        hcf (v, r);
    }
    
    printf("H.C.F = %d\n", v);
    
   
}