P1433 代码：

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    int a,b,a1=0,b1=0;
    double dis=0;
    for(int i=1;i<=n;i++){
        cin>>a>>b;
        dis+=sqrt((a1-b1)*(a1-b1)+(a-b)*(a-b));
        a1=a;
        b1=b;
    }
    cout<<fixed<<setprecision(2)<<dis<<endl;
    return 0;
    
}