https://www.acmicpc.net/problem/2445
const fs=require('fs')
n=parseInt(fs.readFileSync(0).toString())
for(i=1;i<=n;i++){
for(j=0;j<i;j++) process.stdout.write("*");
for(j=(n-i)*2;j>0;j--) process.stdout.write(" ");
for(j=0;j<i;j++) process.stdout.write("*");
console.log();
}
for(i=n-1;i>=1;i--){
for(j=0;j<i;j++) process.stdout.write("*");
for(j=(n-i)*2;j>0;j--) process.stdout.write(" ");
for(j=0;j<i;j++) process.stdout.write("*");
console.log();
}