var input = require("fs").readFileSync("input_2.txt").toString().replace(/\r/g, "");
var cogs = input.split("\n").filter((a)=>(a)).map((line)=>{
  var lineParts = line.match(/Disc #([1-9]+) has ([1-9]+) positions; at time=0, it is at position ([0-9]+)./);
  return {
    number: parseInt(lineParts[1]),
    positions: parseInt(lineParts[2]),
    startPos: parseInt(lineParts[3]),
  };
}).sort((a, b)=>(a.number - b.number));

var t = -1;
var solved = false;
while(!solved){
  solved = true;
  t++;
  for(var cog of cogs){
    if(((cog.number + cog.startPos + t) % cog.positions) != 0){
      solved = false;
    }
  }
}
console.log(t);