#include "bits/stdc++.h" using namespace std; #define int long long #define FOR(i, a, b) for(int i=(a);i<(b);i++) #define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--) #define REP(i, n) for(int i=0; i<(n); i++) #define RREP(i, n) for(int i=(n-1); i>=0; i--) #define ALL(a) (a).begin(),(a).end() #define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end()); #define CONTAIN(a, b) find(ALL(a), (b)) != (a).end() #define array2(type, x, y) array, x> #define vector2(type) vector > #define out(...) //printf(__VA_ARGS__) typedef pair pos; int pos::*x = &pos::first; int pos::*y = &pos::second; int dxy[] = {0, 1, 0, -1, 0}; /*================================*/ int N; signed main() { #if DEBUG std::ifstream in("input.txt"); std::cin.rdbuf(in.rdbuf()); #endif cin >> N; vector A(N); REP(i, N) cin >> A[i]; int t = N; RREP(i, N) { if (A[i] == t) t--; } cout << t << endl; return 0; }