#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int main(void) {
	int testCase;
	scanf("%d", &testCase);
	for (int i = 0; i < testCase; i++) {
		int rePlay;
		char str[21];
		scanf("%d %s", &rePlay, &str);
		char P[161];
		for (int j = 0; j < strlen(str); j++) {
			for (int k = rePlay * j; k < rePlay * strlen(str); k++) {
				if (k / rePlay == j) P[k] = str[j];
				else break;
			}
		}
		for (int j = 0; j < rePlay * strlen(str); j++) {
			printf("%c", P[j]);
		}
		printf("\n");
	}
	system("pause");
	return 0;
}

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