Solution of LIGHT OJ 1241 :: Pinocchio

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/**Bismillahir Rahmanir Rahim.**/

#include <stdio.h>
#include <math.h>
int main()
{
    int tst, i, j;
    double a;
    scanf("%d", &tst);
    for(i=1; i<=tst; i++)
    {
        int n, cnt=0;
        scanf("%d", &n);
        int ara[n];
        for(j=0; j<n; j++)
            scanf("%d", &ara[j]);
        a = ara[0]-2;
        cnt = ceil(a/5.0);
        for(j=1; j<n; j++)
        {
            a = ara[j]-ara[j-1];
            cnt += ceil(a/5.0);
        }
        printf("Case %d: %d\n", i, cnt);
    }
    return 0;
}