#include <stdio.h>
#include <time.h>

int goDown(int n) {
    if (n == 1) {
        return 1;
    }
    else if (n == 2) {
        return 2;
    }
    else if (n == 3) {
        return 4;
    }
    else {
        return goDown(n-1) + goDown(n-2) + goDown(n-3);
    }
}

int main() {
    int n = 0;
    int i = 0, j = 0;
    int startTime, finishTime;
    double time;
    double timeSum;
    int ans;
    for (i = 5; i < 21; i++) {
        printf("%d: %d\n", i, goDown(i));
    }
    for (j = 15; j <=35; j+=10) {
        printf("n = %d\n", j);
        for (i = 0; i < 3; i++) {
            startTime = clock();
            ans = goDown(j);
            finishTime = clock();
            time = ((double)finishTime - startTime) / CLOCKS_PER_SEC;
            timeSum += time;
            printf("%.16lf\n", time);
        }
        printf("Avg: %lf\n", timeSum/3);
        timeSum = 0;
    }
    return 0;
}