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#include <cstdio>
#include <algorithm>

bool coin[201718+1+20];
int N;
int largest = 0;

int main() {
    scanf("%d", &N);
    for (int i=0; i<N; i++) {
        int x; scanf("%d", &x);
        while (coin[x])
            coin[x] = false, x++;
        coin[x] = true;
        largest = std::max(largest, x);
    }
    
    printf("%d\n", largest);
    
    return 0;
}