#include<cstdio>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
int main(){
    int N;
    scanf("%d", &N);
    int R[N-1];
    for(int i = 0; i < N-1; ++i) scanf("%d", R + i);
    int left = 0, right, answer = 0, mx = R[0]-1;
    while(left < N-1){
        answer++;
        if(mx == N-1) break;
        right = mx;
        while(left < right && left < N-1){
            left++;
            chmax(mx, R[left]-1);
        }
    }
    printf("%d\n", answer);
}