#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int a=1,b=1,c=1,k,i=3; cin>>k; while(i<=k){ c=a+b; a=b; b=c; i++; } cout<<c; return 0; }