public static long moduloexpo2(long x, int n, int p) {
      long resul = 0;
      if(n == 1){
          resul = modulo2(x, p);
      }else{
          int i = (int)(n/2);
          cpt ++;
          if(n == 2*i){
              long temp = moduloexpo2(x,i,p);
              resul = modulo2(temp*temp, p);
              cpt += 1;
          }else{
              long temp = moduloexpo2(x,i,p);
              resul = modulo2(modulo2(x,p)*temp*temp, p);
              cpt += 2;
          }
      }
      return resul;
  }