#!/bin/bash

read line
target=( $(sed 's/^.*x=\(.*\)\.\.\(.*\), y=\(.*\)\.\.\(.*\)/\1 \2 \3 \4/' <<< $line) )

possible_x=()
for ((i=1;i<target[1];i++)); do
  velocity_x=$i
  position_x=0
  while [ $velocity_x -gt 0 ] && [ $position_x -lt ${target[0]} ]; do
    position_x=$((position_x+velocity_x))
    velocity_x=$((velocity_x-1))
  done
  if [ $position_x -ge ${target[0]} ] && [ $position_x -le ${target[1]} ]; then
    possible_x+=( $i )
  fi
done

highest_y=0
for ((i=0;i<${#possible_x[@]};i++)); do
  temp_highest_y=0
  possible_y=$((target[2]*(-1)-1))
  for ((j=$possible_y;j>0;j--)); do
    velocity_x=${possible_x[$i]}
    velocity_y=$j
    position_x=0
    position_y=0
    while [ $position_x -le ${target[1]} ] && [ $position_y -ge ${target[2]} ]; do
      position_x=$((position_x+velocity_x))
      position_y=$((position_y+velocity_y))
      velocity_x=$((velocity_x-1))
      if [ $velocity_x -lt 0 ]; then
        velocity_x=0
      fi
      velocity_y=$((velocity_y-1))
      if [ $position_y -gt $temp_highest_y ]; then
        temp_highest_y=$position_y
      fi
      if [ $position_x -ge ${target[0]} ] && [ $position_y -ge ${target[2]} ] \
              && [ $position_x -le ${target[1]} ] && [ $position_y -le ${target[3]} ]; then
        if [ $temp_highest_y -gt $highest_y ]; then
          highest_y=$temp_highest_y
        fi
        break
      fi
    done
  done
done

echo $highest_y