#import <Foundation/Foundation.h>
#import <stdio.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        int X,t;
        scanf("%d %d",&X,&t);
        NSString *answer=[NSString stringWithFormat:@"%d",(X-t>=0)?X-t:0];
        
        NSFileHandle *fileHandle = [NSFileHandle fileHandleWithStandardOutput];
        [fileHandle writeData:[answer dataUsingEncoding:NSUTF8StringEncoding]];
        [fileHandle writeData:[@"\n" dataUsingEncoding:NSUTF8StringEncoding]];
        [fileHandle closeFile];
    }
    return 0;
}
