#include <stdio.h>

int fib ( int n ) {
  if ( n==0 || n==1 ) {
    return 1;
  } else {
    return fib(n-1) + fib(n-2);
  }
}

int fibonacci ( int n ) {
  int back1=1, back2=1;
  int i, fi;

  if ( n==0 || n==1 ) {
    return 1;
  } else {
    for( i=2; i<=n; i++ ) {
      fi=back2+back1;
      /*printf("%i: %i %i %i\n", i, back2, back1, fi);*/
      back2=back1;
      back1=fi;
    }
    return fi;
  }
}

int main () {
  printf("%i\n", fibonacci(10) );
  return 0;
}