#include <stdio.h>

int tri(int n) {
    if (n == 0) {
        return 0;
    } else if (n == 1) {
        return 0;
    } else if (n == 2) {
        return 1;
    } else {
        return tri(n - 1) + tri(n - 2) + tri(n - 3);
    }
}

int main(void) {
    int n = 6;
    printf("T%d = %d\n", n, tri(n));
    return 0;
}