const int N = 200002;
typedef long long LL;
const int INF = 0x7fffffff;

LL a [N];
int b [N], mo [N][2], cnt;

inline bool cmp ( int x, int y ){
    return a [x] < a [y];
}

int main (){
    int n; rd ( n );
    for ( int i = 1; i <= n; ++i ) lrd ( a [i] );
    for ( int i = 1; i <= n; ++i ) b [i] = i;
    sort ( b+1, b+n+1, cmp );
    for ( int i = 1; i <= n; ){
        int j = i; int mn = INF, mx = -INF;
        while ( j <= n && a [ b [i] ] == a [ b [j] ] ){
            mn = min ( mn, b [j] );
            mx = max ( mx, b [j] );
            j ++;
        }
        mo [++cnt][0] = mn; mo [cnt][1] = mx;
        i = j;
    }
    mo [++cnt][0] = INF; mo [cnt][1] = INF;
    mo [0][0] = mo [0][1] = INF;
    int now = mo [0][0], ans = 0; bool d = true;
    for ( int i = 1; i <= cnt; ++i ){
        if ( d ){
            if ( mo [i][1] < now ) now = mo [i][0];
            else{ ans ++; d = false; now = mo [i][1]; }
        }else{
            if ( mo [i][0] > now ) now = mo [i][1];
            else{ d = true; now = mo [i][0]; }
        }
    }
    printf ( "%d", ans ); return 0;
}
//18 635 -79 -117 620 767 -340 -209 514 509 208 169 500 275 -88 -678 635 122 -220

注意20-24行，sort后不一定保证下标不变，当然也可以写个cmp函数（如下）。

inline bool cmp ( int x, int y ){
    if ( a [x] == a [y] ) return x < y;
    return a [x] < a [y];
}