@Override
    public String toString(){
        String str = "";
        str += "[";
        for(int i = 0; i < x; i++){
            for(int j = 0; j < y; j++){
                str += mat[i][j];
                if(j < y-1){str += ",";}
            }
            if(i < x-1){str += ";";}
        }
        str += "]";
        return str;
    }