#include <iostream>
#include <cstdlib>
#include <cstring>
using namespace std;

char * function(char *d, char *z, char *filter){
    int x = strlen(z) + 1; int y = strlen(filter) + 1; bool b = false;
    for( ; *z ; z++, d++){
        for( ; *filter ; filter++){
            if(*z == *filter)
                b = true;
        }
        if(b)
            *d=*z;
        b = false;
        filter-=y;
    }
    return d;
}

int main(){
    char d[80];
    cout << function(d, "abbccddeeefa", "abd");
    return EXIT_SUCCESS;
}