last digit of n to the power k

#include<stdio.h>
#include<string.h>

int main()
{
    char n[99999];
    long long k, i, prod = 1;
    printf("Enter the number: ");
    scanf("%s", n);
    printf("Enter the power: ");
    scanf("%lld", &k);

    if((n[strlen(n) - 1]) == '0' || (n[strlen(n) - 1]) == '1' || (n[strlen(n) - 1]) == '5' || (n[strlen(n) - 1]) == '6') printf("%c\n", (n[strlen(n) - 1]));
    else if((n[strlen(n) - 1]) == '2')
    {
        if(k % 4 == 0) printf("6\n");
        else if(k % 4 == 1) printf("2\n");
        else if(k % 4 == 2) printf("4\n");
        else if(k % 4 == 3) printf("8\n");
    }
    else if((n[strlen(n) - 1]) == '3')
    {
        if(k % 4 == 0) printf("1\n");
        else if(k % 4 == 1) printf("3\n");
        else if(k % 4 == 2) printf("9\n");
        else if(k % 4 == 3) printf("7\n");
    }
    else if((n[strlen(n) - 1]) == '4')
    {
        if(k % 2 == 0) printf("6\n");
        else if(k % 2 == 1) printf("4\n");
    }
    else if((n[strlen(n) - 1]) == '7')
    {
        if(k % 4 == 0) printf("1\n");
        else if(k % 4 == 1) printf("7\n");
        else if(k % 4 == 2) printf("9\n");
        else if(k % 4 == 3) printf("3\n");
    }
    else if((n[strlen(n) - 1]) == '8')
    {
        if(k % 4 == 0) printf("6\n");
        else if(k % 4 == 1) printf("8\n");
        else if(k % 4 == 2) printf("4\n");
        else if(k % 4 == 3) printf("2\n");
    }
    else if((n[strlen(n) - 1]) == '9')
    {
        if(k % 2 == 0) printf("1\n");
        else if(k % 2 == 1) printf("9\n");
    }
}