Submission

Score: 100

User: Karatat007

Problemset: อนุกรม

Language: cpp

Time: 0.002 second

Submitted On: 2026-09-17 16:26:45

#include <bits/stdc++.h>
using namespace std;

void print128(__int128 x){
    if(x==0){cout<<"0";return;}
    string s;
    while(x>0){ s+=char('0'+(int)(x%10)); x/=10; }
    reverse(s.begin(), s.end());
    cout<<s;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int n; cin>>n;
    __int128 a=1,b=1;
    if(n==1||n==2){cout<<1;return 0;}
    for(int i=3;i<=n;i++){ __int128 c=a+b; a=b; b=c; }
    print128(b);
}