#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 g=3,a=1,b=1,c,k; cin>>k; if(k<=2){ cout<<"1"; } else{ while(g<=k){ c=a+b; a=b; b=c; g++; } cout<<c; } return 0; }