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

int solution(int* nums, int numsSize) {
    // Find longest sequential prefix
    int prefixLen = 1;
    for (int i = 1; i < numsSize; i++) {
        if (nums[i] == nums[i-1] + 1) {
            prefixLen++;
        } else {
            break;
        }
    }
    
    // Calculate prefix sum
    int prefixSum = 0;
    for (int i = 0; i < prefixLen; i++) {
        prefixSum += nums[i];
    }
    
    // Find smallest missing integer >= prefixSum
    int candidate = prefixSum;
    while (true) {
        bool found = false;
        for (int i = 0; i < numsSize; i++) {
            if (nums[i] == candidate) {
                found = true;
                break;
            }
        }
        if (!found) {
            return candidate;
        }
        candidate++;
    }
}

void parseArray(const char* str, int* arr, int* size) {
    *size = 0;
    const char* p = str;
    while (*p && *p != '[') p++;
    if (*p == '[') p++;
    while (*p && *p != ']') {
        while (*p == ' ' || *p == ',') p++;
        if (*p == ']' || *p == '\0') break;
        arr[(*size)++] = (int)strtol(p, (char**)&p, 10);
    }
}

int main() {
    char line[10000];
    fgets(line, sizeof(line), stdin);
    line[strcspn(line, "\n")] = 0;
    
    int nums[1000];
    int numsSize = 0;
    char* token = strtok(line, "[],");
    while (token != NULL) {
        nums[numsSize++] = atoi(token);
        token = strtok(NULL, "[],");
    }
    
    printf("%d\n", solution(nums, numsSize));
    return 0;
}