include <stdio.h>

int main() {

int a, b, c, d, e;
scanf("%d", &a);
e = a % 10;
a = a / 10;
d = a % 10;
a = a / 10;
c = a % 10;
a = a / 10;
b = a % 10;
if (d + b == e + c) {
	printf("YES");
} else {
	printf("NO");
}
return 0;

}