C :

#include <stdio.h>
int main()
{
   int n,m;
   while(~scanf("%d",&n))
   {
       if(n<4)
       {

       printf("%d\n",n);
       }
       else
       {

       m=n-1;
       printf("%d\n",m);
       }




   }

return 0;
}

C++ :

#include <stdio.h>

int main()

{
    int n;
    while(~scanf("%d",&n))
    {
        int cnt  = n;
        for(int i = 1;i <= n;++i)
        {
            int t = i;
            while(t)
            {
                int r = t % 10;
                if(r == 4)
                    cnt--;
                t /= 10;
            }
        }
        printf("%d\n",cnt);
    }
    return 0;
}