C++ :

#include <stdio.h>
#include <algorithm>
using namespace std;

int a[1005];
int sub[1005];

int main()
{
    //freopen("a.in","r",stdin);
    //freopen("a.out","w",stdout);
    int i,j,n,T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        for (i=0;i<n;i++)
        {
            scanf("%d",&a[i]);
        }
        if (n==1) {printf("Too Many\n");continue;}
        if (n==2 && a[0]==a[1]) {printf("%d\n",a[0]);continue;}
        if (n==2) {printf("Too Many\n");continue;}

        for (i=0;i<n-1;i++)
        {
            sub[i]=a[i+1]-a[i];
        }
        for (i=0;i<n-1;i++)
        {
            if (sub[i]!=0) break;
        }
        if (i==n-1) {printf("%d\n",a[0]);continue;}
        if (sub[0]==0) {printf("Bad String\n");continue;}
        int prev;
        for (i=0;i<n-2;i++)
        {
            if (sub[i]!=0 && sub[i+1]%sub[i]!=0) break;
            if (i==0) prev=sub[i+1]/sub[i];
            else if (sub[i+1]!=sub[i]*prev) break;
        }
        if (i<n-2) printf("Bad String\n");
        else
        {
            int A=prev;
            int B=a[1]-a[0]*A;
            printf("%d\n",a[n-1]*A+B);
        }
    }
    return 0;
}