#include <stdio.h>

int Fibonacci(int n){
    int a = 1, b = 2, c;
    if(n == 1 || n == 0) return a;
    if(n == 2) return b;
    for(int i = 2; i < n; i++){
        c = a + b;
        a = b;
        b = c;
    }
    return c;
}    
    
int main(){
    int n;
    scanf("%d", &n);

    printf("%d", Fibonacci(n));
    return 0;
}

莫非是因为我少了换行吗