Unrecognized input: 10 RUB + 10 USD + 10 INR

## Input that failed to parse

```
10 RUB + 10 USD + 10 INR
```

## Error message

```
Cannot convert INR to RUB: No exchange rate available
```

## Expected behavior

Please describe what you expected the calculator to do with this input.

All required exchange rates should be available via real API of central banks.