#include <bits/stdc++.h>

namespace Math {
  static uint64_t gcd(uint64_t x, uint64_t y) {
    while( y != 0 ) {
      x %= y;
      std::swap(x, y);
    }
    return x;
  }
  static uint64_t lcm(uint64_t x, uint64_t y) {
    return x / gcd(x, y) * y;
  }
};

int main() {
  uint64_t x, y;
  scanf("%lu %lu", &x, &y);
  printf("%lu\n", x / Math::gcd(x, y) - 1);
  
  return 0;
}