#include<stdio.h>
#define s1 (STEP+1)%2
#define s0 STEP%2
int main()
{
	int N,a[2][100]={0},STEP=0;
	char M[100];
	int i=-1,x,y,k;
	scanf("%d\n",&N);
	do{
		scanf("%c",&M[++i]);
	}while(M[i]!='\n');
	y=i-1;
	while(i>=0){
		if(M[i]>='a')
			a[0][i]=M[i]-'a'+10;
		else if(M[i]>='A')
			a[0][i]=M[i]-'A'+10;
		else
			a[0][i]=M[i]-'0';
		i--;
	}
	while(STEP<30){
		i=y;
		for(x=0;x<=i/2;x++)
			if(a[s0][x]!=a[s0][i-x])
				break;
		if(x>i/2)
		{
			printf("STEP=%d",STEP);
			return 0;
		}
		x=y=a[s1][0]=0;
		do{
			a[s1][y]+=a[s0][i-x]+a[s0][x];
			k=a[s1][y]/N;
			a[s1][y]%=N;
			a[s1][++y]=k;
			x++;
		}while(x<=i);
		
		if(!a[s1][y])
			y--;
		//printf("%d=",STEP);for(x=0;x<=y;x++)printf("%d ",a[s1][x]);printf("\n");
		STEP++;
		}
	printf("Impossible!");
}