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#include <iostream>

int index(int i,int j){
    return i * (i - 1) / 2 + j;
}

void floydWarshall(int *autostrady,int *distances, int n) {
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < i; j++) {
            if (autostrady[index(i,j)] == 0 && i != j) {
                distances[index(i,j)] = 401;
            } else {
                distances[index(i,j)] = autostrady[index(i,j)];
            }
        }
    }

    for (int k = 0; k < n; k++) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < i; j++) {
                int ij = index(i, j);
                int ik = (i > k) ? index(i, k) : index(k, i);
                int kj = (k > j) ? index(k, j) : index(j, k);
                
                if (distances[ij] > distances[ik] + distances[kj]) {
                    distances[ij] = distances[ik] + distances[kj];
                }
            }
        }
    }
}
int searchMax(int *distances, int size){
    int max = 0;
    for(int i = 0; i<size; i++){
        if(distances[i] > max){
            max = distances[i];
        }
    }
    return max;
}


int main(){
    int n;
    scanf("%d", &n);
    

    for(int m = 0; m<n; m++){
        int t;
        scanf("%d", &t);
        int size = (t*t-t)/2;
        int* autostrady = new int[size]();
        int counter = 0;
        bool zero = false;

        for (int i = 0; i < t; i++) {
            for (int j = 0; j < t; j++) {
                char num;
                scanf(" %c", &num);
                if (j < i) {
                    if(num == '0') zero = true;
                    autostrady[counter] = num - '0';
                    counter++;
                }
            }
        }

        if(!zero){
            printf("1\n");
            delete[] autostrady;
            continue;
        }


        int minGlobal = 401;
       
        for (int s = 0; s<size; s++){
            int* distances = new int[size]();
            if(autostrady[s] ==0){
                autostrady[s] = 1;
            
                floydWarshall(autostrady,distances,t);
                int max = searchMax(distances,size);

                if(max<minGlobal){
                    minGlobal = max;
                }
                delete[] distances;
                autostrady[s] = 0;
            }
        }
        

        

        
        printf("%d\n",minGlobal);
        


        delete[] autostrady;


    }
    return 0;
}