小杨的机器人正在能量踏板上跳跃，踏板编号为1,2,3,...，跳到第n块踏板的方案数满足递推式f(n)=f(n-1)+f(n-2)。若f(1)=1, f(2)=2，则运行以下代码计算jump(5)的结果是?
int jump(int n) {
if (n <= 2)
return n;
int a = 1, b = 2, c = 0;
for (int i = 3; i <= n; i++) {
c = a + b;
a = b;
b = c;
}
return c;
}
