const reader = require("readline").createInterface({
  input: process.stdin,
  output: process.stdout
});
let lines = [];
reader.on("line", line => {
  lines.push(line);
});
reader.on("close", () => {
  const newArr = lines[0].split(' ')
  // const newArr = lines[0].split(' ').map(str => Number(str, 10))
  console.log(newArr)
  let newArrBig1 = BigInt(newArr[0])
  let newArrBig2 = BigInt(newArr[1])
  let newArrBig3 = BigInt(newArr[2])
  console.log(newArrBig1)
  console.log(newArrBig2)
  console.log(newArrBig3)
  // const maxValue = 9007199254740991
  // if (newArr[2] > maxValue) {
  //   let biggest = BigInt(newArr[2])
  //   console.log(biggest)
  // }
  if (newArrBig3 >= newArrBig2) {
    console.log(newArrBig3 - 2n)
  } else if (newArrBig3 < newArrBig2) {
    console.log(newArrBig3 - 1n)
  } else if (newArrBig3 <= newArrBig1) {
    console.log(0)
  }
});