/*#include <stdio.h>
int main()
{
int a,b;
scanf("%d %d",&a,&b);
printf("%d",a%b);
return 0;
}
*/
/*#include <stdio.h>
int main()
{
int a,b;
scanf("%d %d", &a,&b);
printf("%d\n", a+b);
printf("%d\n", a-b);
printf("%d\n", a*b);
printf("%d\n", a/b);
printf("%d\n", a%b);
printf("%.2f", (float)a/b);
return 0;
}
*/
/*#include <stdio.h>
int main()
{
int a,b,c;
scanf("%d %d %d", &a,&b,&c);
printf("%d\n", a+b+c);
printf("%.1f", (a+b+c)/3.0);
return 0;
}
*/
/*#include <stdio.h>
int main()
{
int a;
scanf("%d",&a);
printf("%d", a*24);
return 0;
}
*/
#include <stdio.h>
int main()
{
int a,b;
scanf("%d %d",&a,&b);
printf("%d",a%b);
return 0;
}