C++80分代码，测5有误，求找茬

代码如下：

#include<bits/stdc++.h>
using namespace std;
double dis(double x1,double y1,double x2,double y2){
    return sqrt(pow((x1-x2),2)+pow((y1-y2),2));
}
int main(){
    int x1,y1,x2,y2,x3,y3;
    cin>>x1>>y1>>x2>>y2>>x3>>y3;
    double d1=dis(x1,y1,x2,y2);
    double d2=dis(x2,y2,x3,y3);
    double d3=dis(x1,y1,x3,y3);
    double c=d1+d2+d3;
    cout << fixed << setprecision(2) << c;
    return 0;
}