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

int solution(int* nums, int size) {
    int moves = 0;
    while (1) {
        // Find first duplicate
        int duplicateIdx = -1;
        for (int i = 0; i < size; i++) {
            for (int j = i + 1; j < size; j++) {
                if (nums[i] == nums[j]) {
                    duplicateIdx = j;
                    break;
                }
            }
            if (duplicateIdx != -1) break;
        }
        
        if (duplicateIdx == -1) break; // No more duplicates
        
        // Increment the duplicate until unique
        while (1) {
            int hasDup = 0;
            for (int i = 0; i < size; i++) {
                if (i != duplicateIdx && nums[i] == nums[duplicateIdx]) {
                    hasDup = 1;
                    break;
                }
            }
            if (!hasDup) break;
            nums[duplicateIdx]++;
            moves++;
        }
    }
    
    return moves;
}

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);
    
    // Parse JSON array manually
    int nums[1000];
    int size = 0;
    char* token = strtok(line, "[,]");
    while (token != NULL) {
        if (strlen(token) > 0 && token[0] >= '0' && token[0] <= '9') {
            nums[size++] = atoi(token);
        }
        token = strtok(NULL, "[,]");
    }
    
    int result = solution(nums, size);
    printf("%d\n", result);
    
    return 0;
}