{"raw_statement":[{"iden":"problem statement","content":"There is a container with $A$ cyan balls. Takahashi will do the following operation as many times as he likes (possibly zero times):\n\n*   add $B$ cyan balls and $C$ red balls into the container.\n\nTakahashi's objective is to reach a situation where the number of cyan balls in the container is at most $D$ times the number of red balls in it.\nDetermine whether the objective is achievable. If it is achievable, find the minimum number of operations needed to achieve it."},{"iden":"constraints","content":"*   $1 \\leq A,B,C,D \\leq 10^5$\n*   All values in input are integers."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$A$ $B$ $C$ $D$"},{"iden":"sample input 1","content":"5 2 3 2"},{"iden":"sample output 1","content":"2\n\nBefore the first operation, the container has $5$ cyan balls and $0$ red balls. Since $5$ is greater than $0$ multiplied by $D=2$, Takahashi's objective is not yet achieved.\nJust after the first operation, the container has $7$ cyan balls and $3$ red balls. Since $7$ is greater than $3$ multiplied by $2$, the objective is still not achieved.\nJust after the second operation, the container has $9$ cyan balls and $6$ red balls. Since $9$ is not greater than $6$ multiplied by $2$, the objective is achieved.\nThus, the answer is $2$."},{"iden":"sample input 2","content":"6 9 2 3"},{"iden":"sample output 2","content":"\\-1\n\nNo matter how many times Takahashi repeats the operation, his objective will never be achieved."}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}