Roma and Lucky Numbers

#include<stdio.h>
#include<math.h>
int main()
{
    int a,i,n,k,t=0,t1=0;
    scanf("%d %d",&n,&k);
    for(i=1;i<=n;i++)
    {
        scanf("%d",&a);
        t1=0;
        while(a!=0)
        {
            if(a%10==4||a%10==7)t1++;
            a/=10;
        }
        if(t1<=k)t++;
    }
    printf("%d",t);
    return 0;
}

http://codeforces.com/contest/262/problem/A