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

int hIndex(int* citations, int n) {
    if (n == 0) return 0;
    
    // Create buckets for citation counts
    int* buckets = (int*)calloc(n + 1, sizeof(int));
    
    // Fill buckets
    for (int i = 0; i < n; i++) {
        if (citations[i] >= n) {
            buckets[n]++;
        } else {
            buckets[citations[i]]++;
        }
    }
    
    // Scan from right to left to find H-Index
    int papersWithAtLeastH = 0;
    for (int h = n; h >= 0; h--) {
        papersWithAtLeastH += buckets[h];
        // Check if we have at least h papers with at least h citations
        if (papersWithAtLeastH >= h) {
            free(buckets);
            return h;
        }
    }
    
    free(buckets);
    return 0;
}

int main() {
    char input[1000];
    fgets(input, sizeof(input), stdin);
    
    int citations[1000];
    int n = 0;
    
    char* token = strtok(input, "[,] \n");
    while (token != NULL && n < 1000) {
        citations[n++] = atoi(token);
        token = strtok(NULL, "[,] \n");
    }
    
    printf("%d\n", hIndex(citations, n));
    return 0;
}