#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>

#define int ptrdiff_t
int N;
main(){
    scanf("%td\n", &N);
    int i = 0;
    while (N!=1)
        i++, N = (N - 1) / 2 + 1;
    printf("%td\n", i);
    return 0;
}