C++ :

#include <stdio.h>
#include <iostream>
#include <math.h>
#include <string>
using namespace std;

int main()
{
	int N;
	int x, y;
	string s;
	int sjz;
	scanf("%d", &N);
	while (N--)
	{
		scanf("%d%d", &x, &y);
		getchar();
		if (y == x || y > 36)
		{
			printf("ERROR");
		}
		else
		{
			cin >> s;
			sjz = 0;
			int result[1000];
			for (int i = s.length() - 1; i >= 0; i--)
			{
				if (s[i]>=65 && s[i]<=91)
					sjz = (s[i] - 55) * (int)pow((double)x, s.length() - i - 1) + sjz;
				else
					sjz = (s[i] - 48) * (int)pow((double)x, s.length() - i - 1) + sjz;
			}
			int yushu;
			int shang;
			int i;
			for (i = 0; sjz != 0; i++)
			{
				yushu = sjz%y;
				sjz = sjz / y;
				result[i] = yushu;
			}
			while (i--)
			{
				if (result[i]>=10)
				   printf("%c", result[i]+55);
				else
					printf("%d", result[i]);
			}
		}	
		if (N != 0)
			printf("\n\n");
	}
	return 0;
}