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

int solution(int* citations, int n) {
    int left = 0, right = n - 1;
    
    while (left <= right) {
        int mid = (left + right) / 2;
        int h = n - mid; // number of papers from position mid to end
        
        if (citations[mid] >= h) {
            // This position could work, try to find earlier position
            right = mid - 1;
        } else {
            // Need more citations, move right
            left = mid + 1;
        }
    }
    
    return n - left;
}

int main() {
    char line[10000];
    fgets(line, sizeof(line), stdin);
    int citations[1000];
    int n = 0;
    char* token = strtok(line + 1, ",]");
    while (token != NULL) {
        citations[n++] = atoi(token);
        token = strtok(NULL, ",]");
    }
    int result = solution(citations, n);
    printf("%d\n", result);
    return 0;
}