#include <stdio.h>
void main(void){
	int fruits[3];
	int fruitsCount[4] = {0,0,0,0};

	for(int i = 0;i < 3;i++){
		scanf("%d",&fruits[i]);
		fruitsCount[fruits[i]]++;
	}
	if(fruits[0] == fruits[1] && fruits[0] == fruits[2]){
		printf("%d",fruits[0]);
	}else if(fruits[0] != fruits[1] && fruits[0] != fruits[2] && fruits[1] != fruits[2]  ){
		for(int i = 0 ; i < 4 ; i++){
			if(fruitsCount[i] != 0){
				continue;
			}
			printf("%d",i);
			break;
		}
	}else{
		for(int i = 0 ; i < 4 ; i++){
			if(fruitsCount[i] != 1){
				continue;
			}
			printf("%d",i);
			break;
		}
	}
}