#include <iostream>

using namespace std;


char* ISSUBSTR( char str1[], char str2[]){

  char *sub = nullptr;
  for( int i = 0; str2[i] != '\0'; i++ ){
    bool flag = true;
    for( int j = 0; str1[j] != '\0'; j++ ){
      if( str1[j] != str2[i+j] )
        flag = false;
    }
    if( flag && sub == nullptr ){
      sub = str2 + i;
    }
  }
  return sub;
}


int main(){

  char str2[] = "ABCDEFGCDE";
  char str1[] = "CDE";
  cout << ISSUBSTR( str1, str2 ) << endl;

  return 0;
}