function Main(input) {
  input = input.split("\n");
  var N = parseInt(input[0]);
  input.shift();
  input.splice(N,input.length);
  var x = input.map(i => i.split(" ").map(i => parseInt(i)));
  var ans=0;
  if(x.length==2){
    var ans = Math.sqrt(Math.pow(x[0][0]-x[1][0],2)+Math.pow(x[0][1]-x[1][1],2))/2;
  }else{
    for(var i=0;i<N;i++){
      for(var j=i+1;j<N;j++){
        for(var k=j+1;k<N;k++){
          var edge = new Array();
          edge.push([Math.pow(x[i][0]-x[j][0],2)+Math.pow(x[i][1]-x[j][1],2),0]);
          edge.push([Math.pow(x[i][0]-x[k][0],2)+Math.pow(x[i][1]-x[k][1],2),1]);
          edge.push([Math.pow(x[k][0]-x[j][0],2)+Math.pow(x[k][1]-x[j][1],2),2]);
          edge.sort(function(a,b){return b[0]-a[0]});
          if(edge[0][0]>edge[1][0]+edge[2][0]){
            if(edge[0][1]==0){
              var cx = (x[i][0]+x[j][0])/2;
              var cy = (x[i][1]+x[j][1])/2;
              var r2 = Math.pow(x[i][0]-cx,2)+Math.pow(x[i][1]-cy,2);
            }else if(edge[0][1]==1){
              var cx = (x[i][0]+x[k][0])/2;
              var cy = (x[i][1]+x[k][1])/2;
              var r2 = Math.pow(x[i][0]-cx,2)+Math.pow(x[i][1]-cy,2);
            }else{
              var cx = (x[j][0]+x[k][0])/2;
              var cy = (x[j][1]+x[k][1])/2;
              var r2 = Math.pow(x[j][0]-cx,2)+Math.pow(x[j][1]-cy,2);
            }
          }else{
            var cy = ((x[k][0]-x[i][0])*(Math.pow(x[i][0],2)+Math.pow(x[i][1],2)-Math.pow(x[j][0],2)-Math.pow(x[j][1],2))-(x[j][0]-x[i][0])*(Math.pow(x[i][0],2)+Math.pow(x[i][1],2)-Math.pow(x[k][0],2)-Math.pow(x[k][1],2)))/(2*(x[k][0]-x[i][0])*(x[i][1]-x[j][1])-2*(x[j][0]-x[i][0])*(x[i][1]-x[k][1]));
            if(x[i][0]!=x[j][0]){
              var cx = ((2*x[i][1]-x[j][1])*cy-Math.pow(x[i][0],2)-Math.pow(x[i][1],2)+Math.pow(x[j][0],2)+Math.pow(x[j][1],2))/(2*(x[j][0]-x[i][0]));
            }else{
              var cx = ((2*x[i][1]-x[k][1])*cy-Math.pow(x[i][0],2)-Math.pow(x[i][1],2)+Math.pow(x[k][0],2)+Math.pow(x[k][1],2))/(2*(x[k][0]-x[i][0]));
            }
            var r2 = Math.pow(x[i][0]-cx,2)+Math.pow(x[i][1]-cy,2);
          }
          var flag=0;
          for(var l=0;l<N;l++){
            if(Math.pow(x[l][0]-cx,2)+Math.pow(x[l][1]-cy,2)>r2){
              flag=1
              break;
            }
          }
          if(flag==0){
            ans = Math.sqrt(r2);
            break;
          }
        }
        if(ans!=0){
          break;
        }
      }
      if(ans!=0){
        break;
      }
    }
  }
  console.log('%s', ans);
  return ans;
}

function debug(n){
  var input = document.getElementById("input"+n).value;
  var ans=Main(input);
  var result="WA";
  if(ans==document.getElementById("output"+n).value.split("\n")[0]){
    result="AC";
  }
  document.getElementById("result"+n).innerHTML=result;
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));