Miserable Parody of a Calculator

Create a function that will handle simple math expressions. The input is an expression in the form of a string.

Examples

calculator("23+4") ➞ 27

calculator("45-15") ➞ 30

calculator("13+2-5*2") ➞ 5

calculator("49/7*2-3") ➞ 11

Notes

• There will be no brackets in the input line.
• No need to calculate mathematical functions (sin, cos, ln...).
• There are no gaps in the expression.