{"raw_statement":[{"iden":"problem statement","content":"Takahashi is visiting a shop specializing in cabbage.\nThe shop sells cabbage for $X$ yen (Japanese currency) per head.  \nHowever, if you buy more than $A$ heads of cabbage at once, the $(A+1)$\\-th and subsequent heads will be sold for $Y$ yen per head.  \n(It is guaranteed that $Y \\lt X$. See Sample Input/Output 1 for clarity.)\nPrint the amount of money needed to buy $N$ heads of cabbage."},{"iden":"constraints","content":"*   $1 \\leq N \\leq 10^5$\n*   $1 \\leq A \\leq 10^5$\n*   $1 \\leq Y \\lt X \\leq 100$\n*   All values in input are integers."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$ $A$ $X$ $Y$"},{"iden":"sample input 1","content":"5 3 20 15"},{"iden":"sample output 1","content":"90\n\nYou need to pay $20$ yen for each of the $1$\\-st through $3$\\-rd heads of cabbage, and $15$ yen for each of the $4$\\-th and $5$\\-th heads of cabbage.  \nThus, you need to pay a total of $20+20+20+15+15 = 90$ yen for the $5$ heads of cabbage."},{"iden":"sample input 2","content":"10 10 100 1"},{"iden":"sample output 2","content":"1000"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}