#include <stdio.h>
#include <stdlib.h>

int main()
{
    FILE *fpIn, *fpOut;
    int nr;

    fpIn = fopen("cifra.in","r");
    if (fpIn == NULL) {
        fprintf(stderr, "Eroare accesare adunare.in\n");
        exit(1);
    }

    fpOut = fopen("cifra.out","w");
    if (fpOut == NULL) {
        fprintf(stderr, "Eroare accesare adunare.out\n");
        exit(1);
    }

    fscanf(fpIn, "%d", &nr);

    while (fscanf(fpIn, "%d", &nr) != EOF) {
        int sum = 0;
        double i;
        for (i=1; i<=nr; i++) {
            sum += (i*i);
        }
        fprintf(fpOut, "%d\n", sum%10);
    }


    fclose(fpIn);
    fclose(fpOut);

    return 0;
}