#include<stdio.h>
#include<stdlib.h>

#define STR_LENGTH 10
#define NUM_INPUT 3
#define IMPOSSIBLE 255

void str_cut(char*, unsigned char*);
unsigned char judge_fee(unsigned char*);
unsigned char judge_area1(unsigned char*, char);
unsigned char judge_area2(unsigned char*, char);
unsigned char judge_area3(unsigned char*, char);
unsigned char judge_area4(unsigned char*, char);

int main(void){
  unsigned char judge_num = 0;
  char str[STR_LENGTH];
  unsigned char coin_num[NUM_INPUT] = {0}; /* [0]:1G玉の枚数 etc */

  fgets(str, sizeof(str), stdin);
  str_cut(str, coin_num);

  judge_num = judge_fee(coin_num);

  if(IMPOSSIBLE != judge_num){
    printf("%d\n", judge_num);
  } else {
    printf("Impossible\n");
  }
  return 0;
}

/*
関数概要：渡された文字列を空白で分離し、数値に変換する
第1引数：文字列
第2引数：文字列から数値に変換して格納する配列
*/
void str_cut(char* str, unsigned char* coin_num){
  int start_str = 0;
  int num = 0; //配列NO
  int i = 0;

  while('\0' != str[i]){
    if(' ' == str[i]){
      str[i] = '\0';
      coin_num[num] = (unsigned char) atoi(&str[start_str]);
      ++num;
      ++i;
      start_str = i;
    }
    ++i;
  }

  coin_num[num] = (unsigned char) atoi(&str[start_str]);
  
  return;
}

/*
関数概要：渡された数値から買い物金額を計算する
第1引数：与えられた数値
戻り値：支払うべき料金(255はimpossible)
*/
unsigned char judge_fee(unsigned char* coin_num){
  char use_coin = 0;
  unsigned char ret = 0;

  use_coin = coin_num[0] + coin_num[1] - coin_num[2];

  if(use_coin < -8){
    ret = judge_area1(coin_num, use_coin);
  } else if((-8 <= use_coin) &&(use_coin < 0)){
    ret = judge_area2(coin_num, use_coin);
  } else if((0 <= use_coin) &&(use_coin < 10)){
    ret = judge_area3(coin_num, use_coin);
  } else {
    ret = judge_area4(coin_num, use_coin);
  }
  return ret;
}

unsigned char judge_area1(unsigned char* coin_num, char use_coin){
  return IMPOSSIBLE;
}

unsigned char judge_area2(unsigned char* coin_num, char use_coin){
  unsigned char ret = 0;

  if(0 == coin_num[1]){
    ret = IMPOSSIBLE;
  } else {
    ret = 9 + use_coin;
  }

  return ret;
}

unsigned char judge_area3(unsigned char* coin_num, char use_coin){
  unsigned char ret = 0;

  if(coin_num[0] >= use_coin){
    ret = use_coin;
  } else {
    ret = coin_num[0] + 10 * (use_coin - coin_num[0]);
  }

  return ret;
}

unsigned char judge_area4(unsigned char* coin_num, char use_coin){
  unsigned char ret = 0;

  if(coin_num[0] >= (use_coin + 1)){
    ret = use_coin - 9;
  } else {
    ret = coin_num[0] + 10 * (use_coin - coin_num[0]);
  }

  return ret;
}