Problem:
Score : 100 points

Problem Statement

We have five variables x_1, x_2, x_3, x_4, and x_5.

The variable x_i was initially assigned a value of i.

Snuke chose one of these variables and assigned it 0.

You are given the values of the five variables after this assignment.

Find out which variable Snuke assigned 0.

Constraints

The values of x_1, x_2, x_3, x_4, and x_5 given as input are a possible outcome of the assignment by Snuke.

Input

Input is given from Standard Input in the following format:

x_1 x_2 x_3 x_4 x_5

Output

If the variable Snuke assigned 0 was x_i, print the integer i.

Sample Input 1

0 2 3 4 5

Sample Output 1

1

In this case, Snuke assigned 0 to x_1, so we should print 1.

Sample Input 2

1 2 0 4 5

Sample Output 2

3

Solution in C (GCC 9.2.1) (judge verdict: Accepted)

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


int compare_int(const void *a, const void *b)
{
    return *(int*)a - *(int*)b;
//    return *(long long*)a - *(long long*)b;
}
//  qsort(A, b, sizeof(int), compare_int);

int compare_string(const void *a, const void *b) {
  return strcmp(*(const char **)a, *(const char **)b);
}
//  qsort(names, 3, sizeof *names, compare_string);

//long long  factorial(long long n) {
//    if (n > 0) {
//        return n * factorial(n - 1);
//    } else {
//        return 1;
//    }
//}
long long  factorial(long long n, long long depth) {
    if (n > 1) {
        depth++;
        return factorial(n / 2, depth);
    } else {
        return depth;
    }
}

int min(int a, int b) {
    if (a > b)
        return b;
    else
        return a;
}

int distance(int a, int b) {
  return abs(a-b)*abs(a-b);
}



//int ()
/*
int triangle(int a, int b, int c){
  if(a<b+c){
    if(b<c+a){
      if(c<a+b){
        printf("1\n");
        return 1;
      }
    }
  }
  printf("1\n");
  return 0;
}
*/

int main()
{
  int  a, b, c, d, e, X, Y ,r;
  //unsigned long long a, b, c, d, e, X, Y;
  //  double  c;
// long long  A[200003]={};
  int  A[200003]={};
  int  B[100003]={};
//  int  C[100003][100001]={};
  int  C[100003]={};

  int  flg=0;

//  char s[101][101]={};
  char s[10000001][11]={};
  char t[100001]={};
//  int N, M;
//  int A[1000000001]={};
//  long long  C[101]={};
  int i,j,k;
  long long p=0,q=0;
  int sosuu[46] ={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199};
  int min =100000001;
  int len=0;
  int l=0;
  int cnt=0;
  int num=0;
  int num1=0;
  int num2=0;
  long long  ans=0;
  int ans_ac=0;
  int ans_wa=0;
  int max=0;
  long long sum=0;
  int addr=0;
  int ptn=0;
  int  tmp=0;
  double per=0; 
//  bool on_off[100]={};
  
//  char alp[26]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
//  b=100;
  //  a=0;
  scanf("%d%d%d%d%d", &A[0], &A[1], &A[2], &A[3], &A[4]);
//  printf("%llu\n",);
  for(i=0;i<5;i++){
    if(A[i]==1) B[0]=1;
    else if(A[i]==2) B[1]=1;
    else if(A[i]==3) B[2]=1;
    else if(A[i]==4) B[3]=1;
    else if(A[i]==5) B[4]=1;  
  }
  for(i=1;i<6;i++){
    if(B[i-1]==0) ans=i;
  }
  printf("%d\n",ans);
return 0;
}