#include <stdio.h>

int main(void) {
    int T[20] = {3, 4, 5, 8, 11, 13, 19, 20, 23, 26, 29, 30, 31, 33, 34, 37, 38, 44, 45, 48};
    int x;
    
    scanf("%d", &x);

    int L = 0;
    int H = 19; 
    int M = (L + H) / 2;

    while ((L <= H) && (x != T[M])) {
        if (x < T[M]) {
            H = M - 1;
        } else {
            L = M + 1;
        }
        M = (L + H) / 2;
    }

    if (x == T[M]) {
        printf("Found at %d\n", M + 1);
    } else {
        printf("Not found\n");
    }

    return 0;
}