const input = require('fs').readFileSync('/dev/stdin', 'utf8').split(/[\s]/);
const nin=()=>{const r = input[0];input.shift();return Number(r)};
const nrin=(n)=>{const a=[];rep(n,()=>a.push(nin()));return a};
const sin=()=>{const r = input[0];input.shift();return String(r);}
const out = (...a) => {console.log(...a);}
const min = (...a) => {return Math.min(...a);}
const rep = (n, callback) => {for(let i = 0;i < n; i++){callback();}}

const main = () => {
  let [a,b] = [...nrin(2)];
  out(Number(a*3+b)/ 2);
}
main();