/*
?* Fibonacci Numbers(斐波納契數列)
?* 1, 1，2，3，5，8，13，21，34，55，89，144，233
?* 求第n個斐波納契數
?*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int ctoi( char src )
{
?switch( src )
?{
?case '1':
??return 1;
?case '2':
??return 2;
?case '3':
??return 3;
?case '4':
??return 4;
?case '5':
??return 5;
?case '6':
??return 6;
?case '7':
??return 7;
?case '8':
??return 8;
?case '9':
??return 9;
?default:
??return 0;
?}
}

void Reverse( char* des, char* src )
{
?int length = 0;
?while( src[length++] != 0 ){}
?length--;

?for( int i = 0; i < length; i++ )
?{
??des[i] = src[length-i-1];
?}
}

int getlength( char* p, char* q )
{
?int length = 0;
?for( int i = 0; p[i] != 0; i++ ){}
?length = i;

?for( i = 0; q[i] != 0; i++ ){}

?return length > i ? length : i;?
}

void add( char* des, char* src1, char* src2 )
{
?char temp1[50];
?char temp2[50];
?char temp3[50];

?for( int i = 0; i < 50; i++ )
??temp1[i] = 0;
?for( i = 0; i < 50; i++ )
??temp2[i] = 0;
?for( i = 0; i < 50; i++ )
??temp3[i] = 0;

?Reverse( temp1, src1 );
?Reverse( temp2, src2 );

?int p = 0;
?int temp;
?int length = getlength( temp1, temp2 );

?for( i = 0; i < length; i++ )
?{
??temp = ctoi( temp1[i] ) + ctoi( temp2[i] ) + p;

??if( temp > 9 )
??{
???itoa( temp - 10, &temp3[i], 10 );
???p = 1;
??}
??else
??{
???itoa( temp, &temp3[i], 10 );
???p = 0;
??}
?}
?if( p != 0 )
??itoa( p, &temp3[i], 10 );?
?
?Reverse( des, temp3 );
}

void main()
{
?char m[50];
?char n[50];
?char sum[50];
?int num ;

?for( int i = 0; i < 50; i++ )
??m[i] = 0;
?for( i = 0; i < 50; i++ )
??n[i] = 0;
?for( i = 0; i < 50; i++ )
??sum[i] = 0;

?m[0] = '1';
?n[0] = '1';
?i = 0;

?while( scanf( "%d", &num ) != EOF )
?{
?while( i < num - 2 )
?{
??add( sum, m, n );

??strcpy( n, m );
??strcpy( m, sum );
??i++;
?}

?printf( "%s\n", sum );
?}
}