function main(arg){
	arg = arg.trim().split(' ');
  	var a = arg[0], b = arg[1], c = arg[2];
  	a = c-(a-b);
  	if(a<0) {
    	a = 0;
    }
  	console.log(a);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));