#include<stdio.h>

int input() {
    int op;

    printf("Type:\n(1) for Fibonacci\n(2) for Factorial\n(3) for Exponentiation\n");
    printf("What operation would you like to perform? ");
    scanf("%d", &op);
    return op;

}

int fibo(int a) {
    if(a == 0)
        return 0;
    else if(a == 1)
        return 1;
    else
        return fibo(a-1) + fibo(a-2);
}

int fact(int a) {
    if (a==0)
        return 1;
    else
        return a*fact(a-1);
}

float expt(float a, int b) {
    if(b==0)
        return 1;
    else if(b==1)
        return a;
    else if(b%2==0)
        return expt(a,b/2) * expt(a,b/2);
    else if(b%2!=0)
        return a * expt(a,(b-1)/2) * expt(a,(b-1)/2);
}

int main() {
    input();

    if(input()==1)
    {
        int a;

        printf("\n****FIBONACCI****\n");
        printf("Input nth term of Fibonacci sequence: ");
        scanf("%d", &a);
        if(a<0)
        {
            printf("Invalid input.\n\n");
            input();
        }
        printf("The term %d of Fibonacci sequence is %d.", a, fibo(a));
    }

    else if(input()==2)
    {
        int a;

        printf("\n****FACTORIAL****\n");
        printf("Input number: ");
        scanf("%d", &a);
        if(a<0)
        {
            printf("Invalid input.\n\n");
            input();
        }
        printf("%d! (factorial) is %d", a, fact(a));
    }

    else if(input()==3)
    {
        float a;
        int b;

        printf("\n****EXPONENTIATION****\n");
        printf("Input base number: ");
        scanf("%f", &a);
        printf("Input exponent: ");
        scanf("%d", &b);
        if(b<0)
        {
            printf("Invalid input.\n\n");
            input();
        }

        printf("%.2f raised to %d is %.2f", a, b, expt(a,b));
    }

    return 0;
}