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

void printAllprefixes(char str[]){
   for(int e = 0; str[e]!='\0'; e++){
    for(int s=0;s<=e;s++){
        cout<<str[s];
    }
    cout<<endl;
   }

}

int main(){
   char str[] = "abcd";
   printAllprefixes(str);
   return 0;
}