#include <stdio.h>

#define max( a, b ) ( ((a) > (b)) ? (a) : (b) )

int main(void) {
    char *str = "10101001";
    int longest0=0, longest1=0;
    for (char *p = str ; *p ; p++) {
        if (*p == '0') {
            longest0++;
        } else { // *p must be 1
            longest1 = max(longest0, longest1)+1;
        }
    }
    printf("%d\n", max(longest0, longest1));
	return 0;
}