1964斐波那契数列

#include <stdio.h>
int main()
{
    int i,n,f;
    int a = 1,b=1;
    scanf("%d",&n);
    if(n<=2)
        printf("1");
    else
    {
        for(i=3;i<=n;i++)
        {
            f = a+b;
            a = b;
            b = f;
        }
        printf("%d",f);
    }
    return 0;
}