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

int max(int a, int b) { return a > b ? a : b; }

int maxScoreSightseeingPair(int* values, int n) {
    int maxScore = 0;
    int maxFirstSpot = values[0] + 0; // values[i] + i for i=0
    
    for (int j = 1; j < n; j++) {
        // Current score using best previous first spot
        int currentScore = maxFirstSpot + values[j] - j;
        maxScore = max(maxScore, currentScore);
        
        // Update best first spot for future iterations
        maxFirstSpot = max(maxFirstSpot, values[j] + j);
    }
    
    return maxScore;
}

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