#include <cstdio>
#include <cmath>

#define incID(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define inc( i, n) incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec( i, n) decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)

typedef long long   signed int LL;
typedef long long unsigned int LU;

template<typename T> void swap(T &x, T &y) { T t = x; x = y; y = t; return; }
template<typename T> T abs(T x) { return (0 <= x ? x : -x); }
template<typename T> T max(T a, T b) { return (b <= a ? a : b); }
template<typename T> T min(T a, T b) { return (a <= b ? a : b); }
template<typename T> bool setmin(T &a, T b) { if(a <= b) { return false; } else { a = b; return true; } }
template<typename T> bool setmax(T &a, T b) { if(b <= a) { return false; } else { a = b; return true; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// ---- ----

char n[10002];
int b[10];

int main() {
	/*
	printf("> ");
	int x, y, z;
	scanf("%d%d", &x, &y);
	printf("gcd(%d, %d) = %d\n", x, y, gcd(x,y) );
	return 0;
	*/
	
	scanf("%s", n);
	int l = 0;
	while(n[l] != '\0') { b[ n[l] - '0' ]++; l++; }
	
	int m = 0;
	inc(i, 10) { if(b[i]) { m++; } }
	
	if(m == 1) {
		printf("%s\n", n);
		return 0;
	}
	
	if(m == 2 && b[0]) {
		inc(i, l - b[0]) { printf("%c", n[0]); }
		printf("\n");
		return 0;
	}
	
	return 1;
	
	int ans = 0;
	incII(i, 0, 9) {
	incID(j, 0, i) {
		if(b[i] && b[j]) {
			ans = gcd(ans, gcd(i, j));
		}
	}
	}
	
	if(ans != 1) { ans *= 9; }
	
	printf("%d\n", ans);
	
	return 0;
}