#include <stdio.h>
main()
{
	int i,ii,j,k;

	printf("binary -> decimal\n");
	printf("input binary number (plus only)=");
	scanf("%d", &i);

	j=1; k=0;
	while(i>0){
		ii=i - (i/10)*10;
		if(ii>=2){
			printf("Not a binary number !!! \n");
			k=0;
			break;
		}
		k=k+j*ii;
		i=i/10;
		j=j*2;
	}

	printf("%d (10)\n", k);
}