#include <stdio.h>
int main(void) {
int a, x, y, z, REST, max,N;
scanf("%d", &a);
x = a / 100;
REST = a % 100;
y = REST / 10;
REST = (a % 100) % 10;
z = REST;
if (x>=y&&x>=z)
max=x;
else if(y>=x&&y>=z)
max=y;
else if(z>=x&&z>=y)
max=z
printf("%d",max);
return 0;
}