use std::io::{self, *};
struct Solution{
}
impl Solution{
pub fn fib(n: i32) -> i32 {
if n <= 2 {
return 1;
}
return Solution::fib(n-1) + Solution::fib(n-2);
}
}
fn main() {
let mut n : i32 = 0;
let mut input = String::new();
io::stdin().read_line(&mut input);
n = input.trim().parse().expect("");
print!("{}", Solution::fib(n));
}

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