#include <stdio.h>
//練習問題D
int func(int a){
	if(a==0){
		return -1;
	}	
	else{
		return 3*func(a-1)+5;
	}
}
int main(void) {
	int n = 3, m;
    m = func(n);
    printf("数列anについて, n=%dのときの値は%d\n", n
, m
); 	return 0;
}
 
				I2luY2x1ZGUgPHN0ZGlvLmg+Ci8v57e057+S5ZWP6aGMRAppbnQgZnVuYyhpbnQgYSl7CglpZihhPT0wKXsKCQlyZXR1cm4gLTE7Cgl9CQoJZWxzZXsKCQlyZXR1cm4gMypmdW5jKGEtMSkrNTsKCX0KfQppbnQgbWFpbih2b2lkKSB7CglpbnQgbiA9IDMsIG07CiAgICBtID0gZnVuYyhuKTsKICAgIHByaW50Zigi5pWw5YiXYW7jgavjgaTjgYTjgaYsIG49JWTjga7jgajjgY3jga7lgKTjga8lZFxuIiwgbiwgbSk7CglyZXR1cm4gMDsKfQo=